Planographic printing plate precursor, planographic printing plate precursor laminate, plate-making method for planographic printing plate, and planographic printing method

ABSTRACT

A planographic printing plate precursor containing in the following order: an aluminum support; an image recording layer; and a protective layer, in which a thickness of the protective layer is 0.2 μm or greater, and in a case where a Bekk smoothness of a surface of an outermost layer at a side where the image recording layer is provided is 1000 seconds or less.

CROSS REFERENCE TO RELATED APPLICATION

This is a continuation of International Application No.PCT/JP2019/029321 filed on Jul. 25, 2019, and claims priorities fromJapanese Patent Application No. 2018-144557 filed on Jul. 31, 2018 andJapanese Patent Application No. 2019-103213 filed on May 31, 2019, theentire disclosures of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates to a planographic printing plateprecursor, a planographic printing plate precursor laminate, aplate-making method for a planographic printing plate, and aplanographic printing method.

2. Description of the Related Art

A planographic printing plate precursor is frequently stored andtransported as a laminate formed by laminating a plurality of sheetsthereof. In this laminate, interleaving paper is typically inserted intothe space between planographic printing plate precursors for the purposeof preventing dislocation in stacking of planographic printing plateprecursors, preventing adhesion between planographic printing plateprecursors, and preventing scratches on a surface of a planographicprinting plate precursor on an image recording layer side. However, in acase where interleaving paper is used, problems of cost increase, adisposal treatment, and the like may occur, and thus the interleavingpaper needs to be removed before an exposure step. Therefore, this mayalso result in risk of a load on a plate-making step and occurrence ofinterleaving paper peeling failure. Further, in a case of removing theinterleaving paper, it is necessary to give consideration such that thesurface of the planographic printing plate precursor on the recordinglayer side is not damaged. Accordingly, development of a planographicprinting plate precursor that can be laminated without interleavingpaper has been required.

JP2007-055224A describes, as a planographic printing plate precursorthat can be laminated without interleaving paper, a planographicprinting plate precursor in which a protective layer or an imagerecording layer serving as an outermost layer contains an inorganiclayered compound, and a laminate obtained by laminating the planographicprinting plate precursor.

SUMMARY OF THE INVENTION

A planographic printing plate precursor (hereinafter, also simplyreferred to as a “precursor”) is typically used by laminating precursorsin a state of interposing interleaving paper between precursors for thepurpose of preventing dislocation in stacking precursors in a case ofproducing precursors, preventing adhesion between precursors, preventingmultiple precursors from being fed in a plate-making step of taking outprecursor from the stack one by one, and preventing scratches in a caseof producing and stacking precursors, performing transportation and in aseries of steps carried out in a case of user plate-making and beforeprinting. However, an aspect in which interleaving paper is not used(also referred to as “elimination of interleaving paper”) is employed insome cases for the purpose of preventing interleaving paper peelingfailure in a case of user plate-making, improving the plate-makingspeed, and reducing the cost.

In a case of elimination of interleaving paper, a planographic printingplate precursor is required to have excellent characteristics such as aproperty of preventing multiple plates from being fed in a step oftaking out a precursor from a stack, a property of preventing falling ofa projection provided on a surface of an outermost layer of theprecursor, a property of preventing scratches caused by a projectionprovided on the surface of the outermost layer of the precursor, and aproperty of preventing development delay caused by a projection providedon the surface of the outermost layer of the precursor. However, in acase where the technique described in JP2007-055224A is employed, sincethe property of preventing multiple plates from being fed is degraded,it is not possible to satisfy all the characteristics described above atthe same time.

An object to be achieved by the present invention is to provide aplanographic printing plate precursor in which all characteristics suchas a property of preventing multiple plates from being fed in a step oftaking out a precursor from a stack, a property of preventing falling ofa projection provided on a surface of an outermost layer of theprecursor, a property of preventing scratches caused by a projectionprovided on the surface of the outermost layer of the precursor, and aproperty of preventing development delay caused by a projection providedon the surface of the outermost layer of the precursor are excellenteven in a case of elimination of interleaving paper, a planographicprinting plate precursor laminate including the planographic printingplate precursor, a plate-making method for a planographic printingplate, and a planographic printing method.

The means for achieving the above-described object includes thefollowing aspects.

<1> A planographic printing plate precursor comprising in the followingorder: an aluminum support; an image recording layer and a protectivelayer, in which a thickness of the protective layer is 0.2 μm orgreater, and in a case where a Bekk smoothness of a surface of anoutermost layer at a side where the image recording layer is provided isdenoted by A seconds, the following Expression (1) is satisfied.A≤1000  (1)

<2> The planographic printing plate precursor according to <1>, in whichthe A seconds as the Bekk smoothness of the surface of the outermostlayer at the side where the image recording layer is provided satisfythe following Expression (2).A≤300  (2)

<3> The planographic printing plate precursor according to <1> or <2>,in which an arithmetic average height Sa of the surface of the outermostlayer at the side where the image recording layer is provided is in arange of 0.3 μm to 20 μm.

<4> The planographic printing plate precursor according to any one of<1> to <3>, in which the protective layer contains particles having anaverage particle diameter of 0.5 μm to m, and an in-plane density of theparticles is 10000 particles/mm² or less.

<5> The planographic printing plate precursor according to <4>, in whichthe average particle diameter of the particles is 1.3 times or greaterthan the thickness of the protective layer.

<6> The planographic printing plate precursor according to any one of<1> to <3>, in which the image recording layer contains particles havingan average particle diameter of 0.5 μm to 20 μm, and an in-plane densityof the particles is 10000 particles/mm² or less.

<7> The planographic printing plate precursor according to any one of<4> to <6>, in which the particles having the average particle diameterof 0.5 μm to 20 μm are at least one kind of particles selected from thegroup consisting of organic resin particles and inorganic particles.

<8> The planographic printing plate precursor according to any one of<1> to <3>, in which a plurality of protrusions containing a polymercompound as a main component are provided on the protective layer.

<9> The planographic printing plate precursor according to any one of<1> to <8>, in which the image recording layer contains an infraredabsorbing agent, a polymerization initiator, a polymerizable compound,and a polymer compound.

<10> The planographic printing plate precursor according to <9>, inwhich the polymer compound is a polymer compound containing at least oneof styrene and acrylonitrile as a constitutional unit.

<11> The planographic printing plate precursor according to <9> or <10>,in which the image recording layer contains two or more kinds ofpolymerizable compounds.

<12> The planographic printing plate precursor according to any one of<1> to <11>, in which the protective layer contains a water-solublepolymer.

<13> The planographic printing plate precursor according to <12>, inwhich the water-soluble polymer is polyvinyl alcohol having asaponification degree of 50% or greater.

<14> The planographic printing plate precursor according to any one of<1> to <13>, in which an arithmetic average height Sa of a surface of anoutermost layer at a side opposite to the side where the image recordinglayer is provided is in a range of 0.1 μm to 20 μm.

<15> The planographic printing plate precursor according to any one of<1> to <14>, in which a total value of the arithmetic average height Saof the surface of the outermost layer at the side where the imagerecording layer is provided and an arithmetic average height Sa of asurface of an outermost layer at a side opposite to the side where theimage recording layer is provided is greater than 0.3 μm and 20 μm orless.

<16> The planographic printing plate precursor according to any one of<1> to <15>, in which in a case where the Bekk smoothness of the surfaceof the outermost layer at the side where the image recording layer isprovided is denoted by A seconds and a Bekk smoothness of a surface ofan outermost layer at a side opposite to the side where the imagerecording layer is provided is denoted by B seconds, the followingExpressions (1), (3), and (4) are satisfied.A≤1000  (1)B≤1000  (3)1/A+1/B≥0.002  (4)

<17> A planographic printing plate precursor laminate which is obtainedby laminating a plurality of the planographic printing plate precursorsaccording to any one of <1> to <16>, in which the outermost layer at theside where the image recording layer is provided and an outermost layerat a side opposite to the side where the image recording layer isprovided are laminated to be directly brought into contact with eachother.

<18> A plate-making method for a planographic printing plate,comprising: image-exposing the planographic printing plate precursoraccording to any one of <1> to <16>; and supplying at least one ofprinting ink and dampening water to remove an unexposed portion of theimage recording layer on a printing press and preparing the planographicprinting plate.

<19> A plate-making method for a planographic printing plate,comprising: image-exposing the planographic printing plate precursoraccording to any one of <1> to <16>; and supplying a developer having apH of 2 to 12 to remove an unexposed portion of the image recordinglayer and preparing a planographic printing plate.

<20> A plate-making method for a planographic printing plate,comprising: image-exposing the planographic printing plate precursoraccording to any one of <1> to <16>; and supplying a developer having apH of 2 to 10 to remove an unexposed portion of the image recordinglayer, in which the method does not include washing with water afterremoval of the unexposed portion.

<21> A planographic printing method comprising: image-exposing theplanographic printing plate precursor according to any one of <1> to<16>; supplying at least one of printing ink and dampening water toremove an unexposed portion of the image recording layer on a printingpress and preparing a planographic printing plate; and performingprinting by the prepared planographic printing plate.

<22> A planographic printing method comprising: image-exposing theplanographic printing plate precursor according to any one of <1> to<16>; supplying a developer having a pH of 2 to 12 to remove anunexposed portion of the image recording layer and preparing aplanographic printing plate; and performing printing by the preparedplanographic printing plate.

<23> A planographic printing method comprising: making a planographicprinting plate by image-exposing the planographic printing plateprecursor according to any one of <1> to <16> and supplying a developerhaving a pH of 2 to 10 to remove an unexposed portion of the imagerecording layer, wherein washing with water is not included afterremoval of the unexposed portion; and performing printing by theprepared planographic printing plate.

<24> A planographic printing plate precursor comprising: an aluminumsupport; and a protective layer, in which a thickness of the protectivelayer is 0.2 μm or greater, and in a case where a Bekk smoothness of asurface of an outermost layer at a side where the protective layer isprovided is denoted by A seconds, the following Expression (1) issatisfied.A≤1000  (1)

<25> The planographic printing plate precursor according to <24>, inwhich an arithmetic average height Sa of the surface of the outermostlayer at the side where the protective layer is provided is in a rangeof 0.3 μm to 20 μm.

<26> The planographic printing plate precursor according to <24> or<25>, further comprising: a non-photosensitive layer between thealuminum support and the protective layer.

<27> A planographic printing plate precursor laminate which is obtainedby laminating a plurality of the planographic printing plate precursorsaccording to any one of <24> to <26>, in which the outermost layer atthe side where the protective layer is provided and an outermost layerat a side opposite to the side where the protective layer is providedare laminated to be directly brought into contact with each other.

<28> A planographic printing method comprising: supplying at least oneof printing ink and dampening water to the planographic printing plateprecursor according to any one of <24> to <26> to remove the protectivelayer on a printing press and preparing a planographic printing plate;and performing printing by the prepared planographic printing plate.

According to the present invention, it is possible to provide aplanographic printing plate precursor in which all characteristics suchas a property of preventing multiple plates from being fed in a step oftaking out a precursor from a stack, a property of preventing falling ofa projection provided on a surface of an outermost layer of theprecursor, a property of preventing scratches caused by a projectionprovided on the surface of the outermost layer of the precursor, and aproperty of preventing development delay caused by a projection providedon the surface of the outermost layer of the precursor are excellenteven in a case of elimination of interleaving paper, a planographicprinting plate precursor laminate including the planographic printingplate precursor, a plate-making method for a planographic printingplate, and a planographic printing method.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a graph showing an example of an alternating waveform currentwaveform diagram used for an electrochemical roughening treatment.

FIG. 2 is a side view illustrating an example of a radial type cell inthe electrochemical roughening treatment carried out using analternating current.

FIG. 3 is a schematic view illustrating an anodization treatment deviceused for an anodization treatment.

FIG. 4 is a schematic view illustrating a structure of an example of adevelopment treatment device that can be suitably used in the presentinvention.

FIG. 5 is a side view illustrating the concept of a brush graining stepused for a mechanical roughening treatment in preparation of an aluminumsupport.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The description of constituent elements below is made based onrepresentative embodiments of the present invention in some cases, butthe present invention is not limited to such embodiments.

In the present specification, a numerical range shown using “to”indicates a range including numerical values described before and after“to” as a lower limit and an upper limit.

In a case where substitution or unsubstitution is not noted in regard tothe notation of a “group” (atomic group) in the present specification,the “group” includes not only a group that does not have a substituentbut also a group that has a substituent. For example, the concept of an“alkyl group” includes not only an alkyl group that does not have asubstituent (unsubstituted alkyl group) but also an alkyl group having asubstituent (substituted alkyl group).

In the present specification, the concept of “(meth)acryl” includes bothacryl and methacryl, and the concept of “(meth)acryloyl” includes bothacryloyl and methacryloyl.

The term “step” in the present specification indicates not only anindependent step but also a step which cannot be clearly distinguishedfrom other steps as long as the intended purpose of the step isachieved.

In the present invention, a combination of two or more preferredembodiments is a more preferred embodiment.

Further, the mass average molecular weight (Mw) and the number averagemolecular weight (Mn) in the present invention are molecular weights interms of polystyrene used as a standard substance, which are detected byusing tetrahydrofuran (THF) as a solvent, a differential refractometer,and a gel permeation chromatography (GPC) analyzer using TSKgel GMHxL,TSKgel G4000HxL, and TSKgel G2000HxL (all trade names, manufactured byTosoh Corporation) as columns, unless otherwise specified.

In the present specification, the term “planographic printing plateprecursor” includes not only a planographic printing plate precursor butalso a key plate precursor. Further, the term “planographic printingplate” includes not only a planographic printing plate prepared byperforming operations such as exposure and development on a planographicprinting plate precursor as necessary but also a key plate. In a case ofa key plate precursor, the operations of exposure, development, and thelike are not necessarily required. Further, a key plate is aplanographic printing plate for attachment to a plate cylinder that isnot used, for example, in a case where printing is performed on a partof a paper surface with one or two colors in color newspaper printing.Further, the key plate may also be referred to as a water plate, a dummyplate, a blank plate, an empty plate, or the like.

Hereinafter, the present invention will be described in detail.

[Planographic Printing Plate Precursor]

A planographic printing plate precursor according to the embodiment ofthe present invention is a planographic printing plate precursorincluding an aluminum support (hereinafter, also simply referred to as a“support”), and an image recording layer and a protective layer in thisorder, in which the thickness of the protective layer is 0.2 μm orgreater, and Expression (1) is satisfied in a case where a Bekksmoothness of a surface of an outermost layer at a side where the imagerecording layer is provided is denoted by A seconds.A≤1000  (1)

As a result of intensive examination conducted by the present inventors,it was found that a planographic printing plate precursor in which allcharacteristics such as a property of preventing multiple plates frombeing fed in a step of taking out a precursor from a stack, a propertyof preventing falling of a projection provided on a surface of anoutermost layer of the precursor, a property of preventing scratchescaused by a projection provided on the surface of the outermost layer ofthe precursor, and a property of preventing development delay caused bya projection provided on the surface of the outermost layer of theprecursor are excellent can be provided in a case where the planographicprinting plate precursor according to the embodiment of the presentinvention employs the above-described configuration.

The mechanism in which the above-described excellent effects areobtained is not clear, but can be assumed as follows. It is consideredthat the planographic printing plate precursor according to theembodiment of the present invention has an effect of preventing multipleplates from being fed because of formation of a gap that allows air toflow into a space between precursors in contact with each other in acase where a stack is formed of a projection provided on the surface ofthe outermost layer such that the A seconds as the Bekk smoothness ofthe surface of the outermost layer at the side where the image recordinglayer is provided satisfy Expression (1). Further, it is considered thatthe falling of a projection, scratches, and development delay areprevented because the planographic printing plate precursor has aneffect of increasing the holding power by sufficiently covering theparticles of the projection with the protective layer, an effect ofenhancing the function of protecting the image recording layer, and aneffect of relieving the stress against the image recording layer fromthe projection, by setting the thickness of the protective layer to 0.2μm or greater.

The planographic printing plate precursor according to the embodiment ofthe present invention includes a support, an image recording layer and aprotective layer in this order. The planographic printing plateprecursor may include an undercoat layer between the support and theimage recording layer. Further, a back coat layer may be provided at theside of the support opposite to the side where the image recording layeris provided.

The planographic printing plate precursor according to the embodiment ofthe present invention may be a planographic printing plate precursorused for on-press development or a planographic printing plate precursorused for development carried out with a developer.

In the planographic printing plate precursor according to the embodimentof the present invention, the thickness of the protective layer is 0.2μm or greater, and Expression (1) is satisfied in a case where the Bekksmoothness of the surface of the outermost layer at the side where theimage recording layer is provided is denoted by A seconds.A≤1000  (1)

The surface of the outermost layer is the surface of the protectivelayer in a case where the protective layer is the outermost layer.

Further, for example, in a case where protrusions described below areformed, the protective layer is the outermost layer and a plurality ofprotrusions containing a polymer compound as a main component may beprovided on the protective layer.

In the planographic printing plate precursor according to the embodimentof the present invention, the thickness of the protective layer is 0.2μm or greater. The thickness of the protective layer is preferably in arange of 0.2 to 10 μm, more preferably in a range of 0.3 to 5 μm, andparticularly preferably in a range of 0.5 to 3 μm.

In the planographic printing plate precursor according to the embodimentof the present invention, the A seconds as the Bekk smoothness of thesurface of the outermost layer at the side where the image recordinglayer is provided satisfy Expression (1).A≤1000  (1)

It is preferable that the A seconds as the Bekk smoothness of thesurface of the outermost layer at the side where the image recordinglayer is provided satisfy Expression (2).A≤300  (2)

It is more preferable that the A seconds as the Bekk smoothness of thesurface of the outermost layer at the side where the image recordinglayer is provided satisfy Expression (2a).A≤100  (2a)

The Bekk smoothness (Bekk seconds) in the present invention is measuredin conformity with JIS P8119 (1998). According to the specific measuringmethod, the measurement was performed with one tenth the amount ofstandard air, that is, an air amount of 1 mL using a Bekk smoothnesstester (manufactured by KUMAGAI RIKI KOGYO Co., Ltd.).

In the planographic printing plate precursor according to the embodimentof the present invention, the arithmetic average height Sa of thesurface of the outermost layer at the side where the image recordinglayer is provided is preferably in a range of 0.3 μm to 20 μm.

In a case where the arithmetic average height Sa of the surface of theoutermost layer at the side where the image recording layer is providedis 0.3 μm or greater, the effect of preventing multiple plates frombeing fed is increased because of formation of a gap that allows air toflow into the space between precursors in contact with each other in acase where a stack is formed. In a case where the arithmetic averageheight Sa of the surface of the outermost layer at the side where theimage recording layer is provided is 20 μm or less, a problem ofdevelopment delay occurring due to damage to the image recording layercaused by the projection being pressed deep into the image recordinglayer in a case of formation of a stack or the like does not occur.Further, in a case where the arithmetic average height Sa thereof is ina range of 0.3 μm to 20 μm, the property of preventing scratches isexcellent.

The arithmetic average height Sa of the surface of the outermost layerat the side where the image recording layer is provided is preferably ina range of 0.3 to 20 μm, more preferably in a range of 0.5 to 10 μm, andparticularly preferably in a range of 0.5 to 7 μm.

In the present invention, the arithmetic average height Sa is measuredin conformity with the method described in ISO 25178. Specifically, thearithmetic average height Sa is obtained by using MICROMAP MM3200-M100(manufactured by Mitsubishi Chemical Systems, Inc.), selecting three ormore sites from the same sample, performing the measurement, andaveraging the obtained values. In regard to the measurement region, aregion having a size of 1 cm×1 cm which has been randomly selected froma surface of the sample is measured.

In the planographic printing plate precursor according to the embodimentof the present invention, the arithmetic average height Sa of thesurface of the outermost layer at the side opposite to the side wherethe image recording layer is provided is preferably in a range of 0.1 μmto 20 μm.

In a case where the arithmetic average height Sa of the surface of theoutermost layer at the side opposite to the side where the imagerecording layer is provided is in a range of 0.1 μm to 20 μm, a problemof development delay occurring due to damage to the image recordinglayer caused by the projection, on the surface of the outermost layer atthe side opposite to the side where the image recording layer isprovided, being pressed deep into the image recording layer in a case offormation of a stack or the like does not occur.

As the surface of the outermost layer at the side opposite to the sidewhere the image recording layer is provided, the surface of the supportat the side opposite to the side where the image recording layer isprovided or a surface of a back coat layer is exemplified.

The arithmetic average height Sa of the surface of the outermost layerat the side opposite to the side where the image recording layer isprovided is preferably in a range of 0.1 to 20 μm, more preferably in arange of 0.3 to 20 μm, still more preferably in a range of 0.5 to m, andparticularly preferably in a range of 0.5 to 7 μm.

In the planographic printing plate precursor according to the embodimentof the present invention, the total value of the arithmetic averageheight Sa of the surface of the outermost layer at the side where theimage recording layer is provided and the arithmetic average height Saof the surface of the outermost layer at the side opposite to the sidewhere the image recording layer is provided is preferably greater than0.3 μm and 20 μm or less.

In a case where the total value of the arithmetic average height Sa ofthe surface of the outermost layer at the side where the image recordinglayer is provided and the arithmetic average height Sa of the surface ofthe outermost layer at the side opposite to the side where the imagerecording layer is provided is greater than 0.3 μm and 20 μm or less,the effect of preventing multiple plates from being fed and the effectof preventing development delay are enhanced.

The total value of the arithmetic average height Sa of the surface ofthe outermost layer at the side where the image recording layer isprovided and the arithmetic average height Sa of the surface of theoutermost layer at the side opposite to the side where the imagerecording layer is provided is more preferably in a range of 0.4 to 20μm, still more preferably in a range of 1 to 20 μm, and particularlypreferably in a range of 1 to 14 μm.

In the planographic printing plate precursor according to the embodimentof the present invention, it is preferable that Expressions (1), (3),and (4) are satisfied in a case where the Bekk smoothness of the surfaceof the outermost layer at the side where the image recording layer isprovided is denoted by A seconds and the Bekk smoothness of the surfaceof the outermost layer at the side opposite to the side where the imagerecording layer is provided is denoted by B seconds.A≤1000  (1)B≤1000  (3)1/A+1/B≥0.002  (4)

In a case where the A seconds as the Bekk smoothness and the B secondsas the Bekk smoothness satisfy Expressions (1), (3), and (4), the effectof preventing multiple plates from being fed is further enhanced.

The B seconds as the Bekk smoothness of the surface of the outermostlayer at the side opposite to the side where the image recording layeris provided are preferably 300 seconds or less and more preferably 100seconds or less.

The value of 1/A+1/B which is the total value of the reciprocal of the Aseconds as the Bekk smoothness of the surface of the outermost layer atthe side where the image recording layer is provided and the reciprocalof the B seconds as the Bekk smoothness of the surface of the outermostlayer at the side opposite to the side where the image recording layeris provided is preferably 0.004 or greater and more preferably 0.01 orgreater.

It is preferable that A and B are small, and the lower limits thereofare not particularly limited, but are preferably greater than 0.

In the planographic printing plate precursor according to the embodimentof the present invention, the embodiment for achieving the requirementthat the A seconds as the Bekk smoothness of the surface of theoutermost layer at the side where the image recording layer is providedsatisfy Expression (1) is not particularly limited, and an embodiment inwhich the outermost layer at the side where the image recording layer isprovided has unevenness such as an embodiment A1, an embodiment A2, oran embodiment A3 described below is preferably exemplified.

Embodiment A1

An embodiment in which the protective layer contains particles having anaverage particle diameter of 0.5 μm to 20 μm and the in-plane density ofthe particles is 10000 particles/mm² or less

Embodiment A2

An embodiment in which the image recording layer contains particleshaving an average particle diameter of 0.5 μm to 20 μm and the in-planedensity of the particles is 10000 particles/mm² or less

Embodiment A3

An embodiment in which a plurality of protrusions containing a polymercompound as a main component are provided on the protective layer

The particles having an average particle diameter of 0.5 μm to 20 μm arenot particularly limited, and at least one kind of particles selectedfrom the group consisting of organic resin particles and inorganicparticles are preferable.

Preferred examples of the organic resin particles include polyolefinssuch as poly(meth)acrylic acid esters, polystyrene and derivativesthereof, polyamides, polyimides, low-density polyethylene, high-densitypolyethylene, and polypropylene; particles formed of synthetic resinssuch as polyurethanes, polyureas, and polyesters; and particles formedof natural polymers such as chitin, chitosan, cellulose, crosslinkedstarch, and crosslinked cellulose.

Among these, synthesis resin particles have advantages that the particlesize can be easily controlled and desired surface characteristics can beeasily controlled by surface modification.

As a method of producing organic resin particles, atomization can alsobe made using a crushing method in a case of a relatively hard resinsuch as polymethyl methacrylate (PMMA), but a method of synthesizingparticles using an emulsion suspension polymerization method ispreferably employed from the viewpoints of ease of controlling theparticle diameter and the precision.

The method of producing organic resin particles is described in detailin “Ultrafine Particle and Materials” edited by Materials ScienceSociety of Japan, published by SHOKABO Co., Ltd., 1993 and“Manufacturing & Application of Microspheres & Powders” supervised byHaruma Kawaguchi, published by CMC Publishing, 2005.

Examples of commercially available products of the organic resinparticles include crosslinked acrylic resins MX-40T, MX-80H3wT, MX-150,MX-180TA, MX-300, MX-500, MX-1000, MX-1500H, MR-2HG, MR-7HG, MR-10HG,MR-3GSN, MR-5GSN, MR-7G, MR-10G, MR-5C, and MR-7GC, and styrylresin-based SX-350H and SX-500H (manufactured by Soken Chemical &Engineering Co., Ltd.), Acrylic resins MBX-5, MBX-8, MBX-12, MBX-15,MBX-20, MB20X-5, MB30X-5, MB30X-8, MB30X-20, SBX-6, SBX-8, SBX-12, andSBX-17 (manufactured by Sekisui Plastics Co., Ltd.), polyolefin resinsand CHEMIPEARL W100, W200, W300, W308, W310, W400, W401, W405, W410,W500, WF640, W700, W800, W900, W950, and WP100 (manufactured by MitsuiChemicals, Inc.).

Examples of the inorganic particles include silica, alumina, zirconia,titania, carbon black, graphite, BaSO₄, ZnS, MgCO₃, CaCO₃, ZnO, CaO,WS₂, MoS₂, MgO, SnO₂, a-Fe₂O₃, a-FeOOH, SiC, CeO₂, BN, SiN, MoC, BC, WC,titanium carbide, corundum, artificial diamond, petroleum stone, garnet,silica stone, tripolite, diatomaceous earth, and dolomite.

As the above-described particles, a particle having a hydrophilicsurface is preferable. Examples of the particle having a hydrophilicsurface include an organic resin particle having a hydrophilic surfaceand an inorganic particle having a hydrophilic surface.

As the organic resin particle having a hydrophilic surface, an organicresin particle coated with at least one inorganic compound selected fromthe group consisting of silica, alumina, titania, and zirconia ispreferable and an organic resin particle coated with silica isparticularly preferable.

It is preferable that an organic resin constituting an organic resinparticle having a hydrophilic surface is at least one resin selectedfrom the group consisting of a polyacrylic resin, a polyurethane-basedresin, a polystyrene-based resin, a polyester-based resin, anepoxy-based resin, a phenolic resin, and a melamine resin.

Hereinafter, the organic resin particle having a hydrophilic surfacewill be described in detail using an organic resin particle coated withsilica (hereinafter, also referred to as a “silica-coated organic resinparticle”) as an example, and the organic resin particle having ahydrophilic surface in the present invention is not limited thereto.

The silica-coated organic resin particle is a particle obtained bycoating the surface of the particle formed of an organic resin withsilica. It is preferable that the organic resin particle constitutingthe core is not softened or sticky due to the moisture in the air or thetemperature thereof.

Examples of the organic resin constituting the organic resin particle inthe silica-coated organic resin particles include a polyacrylic resin, apolyurethane-based resin, a polystyrene-based resin, a polyester-basedresin, an epoxy-based resin, a phenol resin, and a melamine resin.

As a material forming the silica layer covering the surface of thesilica-coated organic resin particle, a compound containing analkoxysilyl group such as a condensate of an alkoxysiloxane-basedcompound, particularly, a siloxane-based material, and specifically,silica particles such as silica sol, colloidal silica, and silicananoparticles are preferably exemplified.

The configuration of the silica-coated organic resin particle may be aconfiguration in which a silica particle adheres to the surface of anorganic resin particle as a solid component or a configuration in whicha siloxane-based compound layer is formed on the surface of an organicresin particle by performing a condensation reaction on analkoxysiloxane-based compound.

Silica does not necessarily cover the entire surface of the organicresin particle, and it is preferable that the surface thereof is coatedwith at least 0.5% by mass or greater of silica with respect to thetotal mass of the organic resin particles. In other words, in a casewhere silica is present on at least a part of the surface of the organicresin particle, improvement in affinity for a coexisting water-solublepolymer such as polyvinyl alcohol (PVA) on the surface of the organicparticle is achieved, falling off of the particle is suppressed even ina case where external stress is applied thereto, and excellent scratchresistance and ease of peeling in a case of lamination without usinginterleaving paper can be maintained. Accordingly, the expression“coated with silica” in the present invention includes a state in whichsilica is present on at least a part of the surface of the organic resinparticle as described above.

The state of the surface being coated with silica can be confirmed bymorphological observation using a scanning electron microscope (SEM) orthe like. Further, the coating amount of silica can be confirmed bydetecting Si atoms through elemental analysis such as fluorescent X-rayanalysis and calculating the amount of silica present therein.

A method of producing silica-coated organic resin particles is notparticularly limited, and examples thereof include a method of forming asilica surface coating layer simultaneously with formation of organicresin particles by allowing silica particles or a silica precursorcompound to coexist with a monomer component which is the raw materialof the organic resin particles; and a method of forming organic resinparticles, physically adhering silica particles to each surface of theorganic resin particles, and fixing the silica particles thereto.

Hereinafter, an example of the method of producing silica-coated organicresin particles will be described. First, silica and a raw materialresin (more specifically, a raw material resin such as a monomer capableof suspension polymerization, a pre-polymer capable of suspensioncrosslinking, or a resin liquid, constituting the above-describedorganic resin) are added to water containing a suspension stabilizerappropriately selected from a water-soluble polymer such as polyvinylalcohol, methyl cellulose, or polyacrylic acid and an inorganicsuspending agent such as calcium phosphate or calcium carbonate, andstirred and mixed with the water to prepare a suspension in which silicaand a raw material resin are dispersed. Here, a suspension having atarget particle diameter can be formed by adjusting the kind, theconcentration, and the stirring rotation speed of the suspensionstabilizer. Next, the suspension is heated to start the reaction, andresin particles are generated by performing suspension polymerization orsuspension crosslinking on the resin raw material. Here, the coexistingsilica is fixed to the resin particle cured by the polymerization or thecrosslinking reaction, particularly, the vicinity of the surface of theresin particle due to the physical properties thereof. Thereafter, thesuspension is subjected to solid-liquid separation, the suspensionstabilizer adhering to the particles is removed by washing, and theparticles are dried. In this manner, silica-coated organic resinparticles to which silica is fixed and which have a desired particlediameter and a substantially spherical shape can be obtained.

As described above, silica-coated organic resin particles having adesired particle diameter can be obtained by controlling the conditionsduring the suspension polymerization or the suspension crosslinking orsilica-coated organic resin particles are generated without strictlycontrolling the conditions and then silica-coated organic particleshaving a desired size can be obtained by a mesh filtration method or thelike.

In regard to the amount of the raw material to be added to the mixtureduring the production of the silica-coated organic particles accordingto the above-described method, in a case where the total amount of theraw material resin and the silica is 100 parts by mass, an aspect inwhich 0.1 parts by mass to 20 parts by mass of the suspension stabilizeris firstly added to 200 parts by mass to 800 parts by mass of waterserving as a dispersion medium, and sufficiently dissolved or dispersedtherein, 100 parts by mass of a mixture of the raw material resin andthe silica is put into the solution, the solution is stirred while thestirring speed is adjusted such that the dispersed particles have apredetermined particle size, and the solution temperature is increasedto 30° C. to 90° C. after the adjustment of the particle size to cause areaction for 1 hour to 8 hours is preferably exemplified.

The above-described method is merely an example of the method ofproducing silica-coated organic resin particles and silica-coatedorganic resin particles obtained by the methods specifically describedin JP2002-327036A, JP2002-173410A, JP2004-307837A, JP2006-038246A, andthe like can also be suitably used in the present invention.

Further, the silica-coated organic resin particles are also available ascommercially available products, and specific examples ofsilica-melamine composite particles include OPTBEADS 2000M, OPTBEADS3500M, OPTBEADS 6500M, OPTBEADS 10500M, OPTBEADS 35005, and OPTBEADS6500S (all manufactured by Nissan Chemical Industries, Ltd.). Specificexamples of silica-acrylic composite particles include ART PEARL G-200transparent, ART PEARL G-400 transparent, ART PEARL G-800 transparent,ART PEARL GR-400 transparent, ART PEARL GR-600 transparent, ART PEARLGR-800 transparent, and ART PEARL J-7P (all manufactured by NegamiChemical Industrial Co., Ltd.). Specific examples of silica-urethanecomposite particles include ART PEARL C-400 transparent, C-800transparent, P-800T, U-600T, U-800T, CF-600T, CF800T (all manufacturedby Negami Chemical Industrial Co., Ltd.) and DYNAMIC BEADS CN5070D andDANPLACOAT THU (both manufactured by Dainichiseika Color & ChemicalsMfg. Co., Ltd.).

Hereinbefore, the organic resin particles used in the present inventionhave been described using the silica-coated organic resin particles asan example, but the same applies to organic resin particles coated withalumina, titania, or zirconia by using alumina, titania, or zirconia inplace of silica.

As the shape of particles, a perfectly spherical shape is preferable,and a flat plate shape or a so-called spindle shape in which anelliptical shape is shown in a projection view may be employed.

In the protective layer of the embodiment A1, the average particlediameter of the particles is preferably in a range of 0.5 to 10 μm andmore preferably in a range of 0.5 to 5 μm.

In the protective layer of the embodiment A1, the average particlediameter of the particles is preferably 1.3 times or greater thethickness of the protective layer. In a case where the average particlediameter of the particles is 1.3 times or greater the thickness of theprotective layer, the property of preventing multiple plates from beingfed is further improved by sufficiently forming projections. Meanwhile,in a case where the size of the projection is unnecessarily large, sincethe property of preventing development delay and the property ofpreventing falling of a projection tend to be degraded, the averageparticle diameter of the particles is suitably 33 times or less thethickness of the protective layer.

The average particle diameter of the particles in the present inventionindicates the volume average particle diameter, and the volume averageparticle diameter is measured using a laser diffraction and scatteringtype particle size distribution meter. Specifically, the measurement isperformed using, for example, a particle size distribution measuringdevice “MICROTRAC MT-3300II” (manufactured by Nikkiso Co., Ltd.).

Further, in the present invention, the average particle diameter ofother particles is set to be measured according to the above-describedmeasuring method unless otherwise specified.

In the protective layer of the embodiment A1, the in-plane density ofthe particles is preferably 100 to 5000 particles/mm² and morepreferably in a range of 100 to 3000 particles/mm².

The in-plane density in the present invention can be confirmed byobserving the surface of the planographic printing plate precursor witha scanning electron microscope (SEM). Specifically, the average valuethereof can be calculated by observing five sites on the surface of theplanographic printing plate precursor with a scanning electronmicroscope (SEM), counting the number of particles, converting thenumber of particles into the number of particles per observation visualfield area with the unit of mm², and acquiring the average valuethereof.

In the image recording layer of the embodiment A2, the average particlediameter of the particles is preferably in a range of 0.7 to 20 μm, morepreferably in a range of 0.7 to 10 μm, and particularly preferably in arange of 0.7 to 5 μm.

In the image recording layer of the embodiment A2, the in-plane densityof the particles is preferably in a range of 100 to 5000 particles/mm²and more preferably in a range of 100 to 3000 particles/mm².

The kind, the production method, the shape, and the like of theparticles used for the image recording layer of the embodiment A2 arethe same as those of the particles used for the protective layer of theembodiment A1.

It is preferable that the polymer compound constituting the protrusionused in the embodiment A3 is at least one polymer compound selected fromthe group consisting of a novolak resin such as a phenol formaldehyderesin, an m-cresol formaldehyde resin, a p-cresol formaldehyde resin, anm-/p-mixed cresol formaldehyde resin, or a phenol/cresol (any of m-, p-,and m-/p-mixed)-mixed formaldehyde resin, a resol resin, a pyrogallolacetone resin, an epoxy resin, a saturated copolymer polyester resin, aphenoxy resin, a polyvinyl acetal resin, a vinylidene chloride copolymerresin, polybutene, polybutadiene, polyamide, an unsaturated copolymerpolyester resin, polyurethane, polyurea, polyimide, polysiloxane,polycarbonate, chlorinated polyethylene, an aldehyde condensation resinof alkyl phenol, polyvinyl chloride, polyvinylidene chloride,polystyrene, a polyacrylate, a carboxyvinyl polymer, an acrylic resincopolymer resin, hydroxy cellulose, hydroxymethyl cellulose, polyvinylalcohol, polyvinylpyrrolidone, cellulose acetate, methyl cellulose, andcarboxymethyl cellulose.

Among these, from the viewpoint of the developability, a water-solublepolymer compound is more preferable. Specific examples thereof include apolyacrylate, a carboxyvinyl polymer, an acrylic resin copolymer resin,hydroxy cellulose, hydroxymethyl cellulose, polyvinyl alcohol, modifiedpolyvinyl alcohol, polyvinylpyrrolidone, cellulose acetate, methylcellulose, and carboxymethyl cellulose.

As the modified polyvinyl alcohol, acid-modified polyvinyl alcoholcontaining a carboxy group or a sulfo group is preferably used.Specifically, the modified polyvinyl alcohol described in JP2005-250216Aor JP2006-259137A is suitable.

The shape and height of the protrusion are not particularly limited aslong as the A seconds as the Bekk smoothness of the surface of theoutermost layer at the side where the image recording layer is providedsatisfy Expression (1).

Examples of the preferable forms of the protrusions in a case of beingformed on the surface of the outermost layer include a stripe coatedfilm, a dot coated film, and a dashed line coated film. However, thepresent invention is not limited to these forms.

A method of forming stripe-like protrusions (stripe coated film) is notparticularly limited, and the protrusions can be easily formed byapplying a composition that contains at least one selected from thegroup consisting of particles and polymer compounds according to atleast one method selected from the group consisting of a bar coatingmethod, an ink jet printing method, a gravure printing method, a screenprinting method, a spray coating method, and a slot die coating method.

A method of forming dot-like protrusions (dot coated film) is notparticularly limited, and the protrusions can be easily formed byapplying a composition that contains at least one selected from thegroup consisting of particles and polymer compounds according to atleast one method selected from the group consisting of a spray coatingmethod, an ink jet printing method, and a screen printing method.

A method of forming dashed line protrusions (dashed line coated film) isnot particularly limited, and the protrusions can be easily formed byapplying a composition that contains at least one selected from thegroup consisting of particles and polymer compounds according to atleast one method selected from the group consisting of an ink jetprinting method and a screen printing method.

In a case where the planographic printing plate precursor according tothe embodiment of the present invention has an outermost layer (forexample, a back coat layer) at the side of the support opposite to theside where the image recording layer is provided, and the outermostlayer contains the particles or the protrusions are formed on theoutermost layer, the B seconds of the Bekk smoothness of the surface ofthe outermost layer and the arithmetic average height Sa of the surfaceof the outermost layer can be adjusted to be in the above-describeddesired ranges. In this manner, the characteristics of the planographicprinting plate precursor according to the embodiment of the presentinvention are more excellent.

<Support>

The planographic printing plate precursor according to the embodiment ofthe present invention includes an aluminum support.

As the support used in the planographic printing plate precursoraccording to the embodiment of the present invention, a known support isused. Among the examples, an aluminum plate which has been subjected toan anodization treatment is preferable and an aluminum plate which hasbeen subjected to a roughening treatment and an anodization treatment ismore preferable.

The roughening treatment and the anodization treatment can be performedaccording to a known method.

The aluminum plate can be subjected to a treatment appropriatelyselected from an expansion treatment or a sealing treatment ofmicropores of an anodized film described in JP2001-253181A orJP2001-322365A or a surface hydrophilization treatment using alkalimetal silicate described in U.S. Pat. Nos. 2,714,066A, 3,181,461A,3,280,734A, and 3,902,734A or polyvinyl phosphonic acid described inU.S. Pat. Nos. 3,276,868A, 4,153,461A, and 4,689,272A as necessary.

The center line average roughness Ra of the support is preferably in arange of 0.10 mm to 1.2 mm.

Further, in the support, the average diameter of micropores in thesurface of the anodized film is preferably in a range of 10 to 100 nm.

It is preferable that the aluminum support includes an aluminum plateand an anodized aluminum film disposed on the aluminum plate.

The aluminum plate (aluminum support) is a dimensionally stable metalcontaining aluminum as a main component and is formed of aluminum or analuminum alloy. Examples of the aluminum plate include a pure aluminumplate, an alloy plate containing aluminum as a main component and atrace amount of foreign elements, and a plastic film or paper on whichaluminum (alloy) is laminated or vapor-deposited. Further, a compositesheet in which an aluminum sheet is bonded onto a polyethyleneterephthalate film as described in JP1973-018327B (JP-S48-018327B) maybe used.

Examples of the foreign elements contained in the aluminum alloy includesilicon, iron, manganese, copper, magnesium, chromium, zinc, bismuth,nickel, and titanium, and the content of the foreign elements in thealloy 10% by mass or less with respect to the total mass of the alloy.As the aluminum plate, a pure aluminum plate is preferable, butcompletely pure aluminum is difficult to produce in terms of smeltingtechnology, and thus the aluminum plate may contain a trace amount offoreign elements.

The composition of the aluminum plate is not limited, and knownmaterials of the related art (for example, JIS A 1050, JIS A 1100, JIS A3103, and JIS A 3005) can be used as appropriate.

The width of the aluminum plate is preferably in a range of 400 mm to2000 mm, and the thickness thereof is preferably in a range of 0.1 mm to0.6 mm. The width or thickness thereof can be appropriately changeddepending on the size of the printing press, the size of the printingplate, the printed material to be obtained, and the like.

(Anodized Film)

The anodized film indicates an anodized aluminum film having microporeswhich is prepared on the surface of the aluminum plate by theanodization treatment. The micropores extend along the thicknessdirection (aluminum plate side, depth direction) from the surface of theanodized film opposite to the aluminum plate.

From the viewpoints of tone reproducibility, printing durability, andblanket stain resistance, the average diameter (average openingdiameter) of the micropores in the surface of the anodized film ispreferably in a range of 7 nm to 150 nm, more preferably in a range of10 nm to 100 nm, still more preferably in a range of 10 nm to 60 nm,particularly preferably in a range of 15 nm to 60 nm, and mostpreferably in a range of 18 nm to 40 nm.

It is preferable that the micropores in the anodized film are formed oflarge-diameter pores extending to a position at a depth of 10 nm to 1000nm from the surface of the anodized film and small-diameter porescommunicating with the bottom portions of large-diameter pores andextending from a position at a depth of 20 nm to 2000 nm from thecommunication position.

Hereinafter, the large-diameter pores and the small-diameter pores willbe described in detail.

—Large-Diameter Pore—

From the viewpoints of tone reproducibility, printing durability, andblanket stain resistance, the average diameter (average openingdiameter) of the large-diameter pores in the surface of the anodizedfilm is preferably in a range of 7 nm to 150 nm, more preferably in arange of 15 nm to 150 nm, still more preferably in a range of 15 nm to60 nm, and particularly preferably in a range of 18 nm to 40 nm.

The average diameter of the large-diameter pores is calculated as anarithmetic average value obtained by observing 4 sheets (N=4) of thesurfaces of the anodized film using a field emission scanning electronmicroscope (FE-SEM) at a magnification of 150000, measuring thediameters of the micropores (large-diameter pores) present in a range of400×600 nm² in the obtained four sheets of images, and averaging thevalues.

Further, in a case where the shape of the large-diameter pores is notcircular, an equivalent circle diameter is used. The “equivalent circlediameter” is a diameter of a circle obtained by assuming the shape of anopening portion of a micropore as a circle having the same projectedarea as the projected area of the opening portion.

It is preferable that the bottom portions of the large-diameter poresare positioned at a depth of 70 nm to 1000 nm (hereinafter, alsoreferred to as a depth A) from the surface of the anodized film. Thatis, it is preferable that the large-diameter pores are pores extendingfrom the surface of the anodized film to a position at a depth of 70 nmto 1000 nm in the depth direction (thickness direction). Among examples,from the viewpoint that the effects of the method of producing theplanographic printing plate precursor according to the embodiment of thepresent invention, the depth A is more preferably in a range of 90 nm to850 nm, still more preferably in a range of 90 nm to 800 nm, andparticularly preferably in a range of 90 nm to 600 nm.

Further, the depth thereof is calculated as an arithmetic average valueobtained by capturing (at a magnification of 150000) an image of a crosssection of the anodized film, measuring the depth of 25 or morelarge-diameter pores, and averaging the obtained values.

The shape of the large-diameter pores is not particularly limited, andexamples thereof include a substantially straight tubular shape(substantially cylindrical shape) and a conical shape whose diameterdecreases toward the depth direction (thickness direction). Among these,a substantially straight tubular shape is preferable. Further, the shapeof the bottom portions of the large-diameter pores is not particularlylimited, but may be a curved shape (projection) or a planar shape.

The inner diameter of the large-diameter pores is not particularlylimited, but it is preferable that the inner diameter thereof isapproximately the same as or smaller than the diameter of the openingportion. Further, the inner diameter of the large-diameter pores may bedifferent from the diameter of the opening portion by 1 nm to 10 nm.

—Small-Diameter Pore—

The small-diameter pores are pores communicating with the bottomportions of the large-diameter pores and extending from thecommunication position in the depth direction (thickness direction). Onesmall-diameter pore typically communicates with one large-diameter pore,but two or more small-diameter pores may communicate with the bottomportion of one large-diameter pore.

The average diameter of the small-diameter pores at the communicationposition is preferably 13 nm or less, more preferably 11 nm or less, andparticularly preferably 10 nm or less. The lower limit is notparticularly limited, but is preferably 5 nm or more.

The average diameter of the small-diameter pores is calculated as anarithmetic average value obtained by observing 4 sheets (N=4) of thesurfaces of the anodized film 20 using a field emission scanningelectron microscope (FE-SEM) at a magnification of 150000, measuring thediameters of micropores (small-diameter pores) present in a range of 400nm×600 nm² in the obtained four sheets of images, and averaging thevalues. Further, in a case where the depth of the large-diameter poresis large, the average diameter of the small-diameter pores may beacquired by cutting the upper portion (a region where large-diameterpores are present) of the anodized film (for example, cutting theportion by argon gas) as necessary and observing the surface of theanodized film 20 using the above-described FE-SEM.

Further, in a case where the shape of the small-diameter pores is notcircular, an equivalent circle diameter is used. The “equivalent circlediameter” is a diameter of a circle obtained by assuming the shape of anopening portion of a micropore as a circle having the same projectedarea as the projected area of the opening portion.

It is preferable that the bottom portions of the small-diameter poresare positioned at a position extending from the communication position(corresponding to the depth A described above) with the large-diameterpores to a position at a depth of 20 nm to 2000 nm in the depthdirection. That is, the small-diameter pores are pores extending fromthe communication position with the large-diameter pores to a positionin the depth direction (thickness direction), and the depth of thesmall-diameter pores is preferably in a range of 20 nm to 2000 nm, morepreferably in a range of 100 nm to 1500 nm, and particularly preferablyin a range of 200 nm to 1000 nm.

Further, the depth thereof is calculated as an arithmetic average valueobtained by capturing (at a magnification of 50000) an image of a crosssection of the anodized film, measuring the depth of 25 or moresmall-diameter pores, and averaging the obtained values.

The shape of the small-diameter pores is not particularly limited, andexamples thereof include a substantially straight tubular shape(substantially cylindrical shape) and a conical shape whose diameterdecreases toward the depth direction. Among these, a substantiallystraight tubular shape is preferable. Further, the shape of the bottomportions of the small-diameter pores is not particularly limited, butmay be a curved shape (projection) or a planar shape.

The inner diameter of the small-diameter pores is not particularlylimited, but it is preferable that the inner diameter thereof may beapproximately the same as the diameter in the communication position ormay be smaller or larger than the diameter in the communicationposition. Typically, the inner diameter of the small-diameter pores maybe different from the diameter of the opening portion by 1 nm to 10 nm.

The ratio of the average diameter of the large-diameter pores in thesurface of the anodized film to the average diameter of thesmall-diameter pores at the communication position (average diameter oflarge-diameter pores in surface of anodized film)/(average diameter ofsmall-diameter pores at communication position) is preferably in a rangeof 1.1 to 13 and more preferably in a range of 2.5 to 6.5.

Further, the ratio of the depth of the large-diameter pores to the depthof the small-diameter pores (depth of large-diameter pores)/(depth ofsmall-diameter pores) is preferably in a range of 0.005 to 50 and morepreferably in a range of 0.025 to 40.

A method of producing the support used in the present invention is notparticularly limited, and a known method can be used.

Hereinafter, a method of producing the support will be exemplified, butit goes without saying that the method is not limited thereto.

As a method of producing an aluminum support, for example, a productionmethod of sequentially performing the following steps is preferable as amethod of producing an aluminum support that includes an anodized filmhaving micropores extending from the surface thereof on the imagerecording layer side in the depth direction.

(Roughening treatment step) A step of performing a roughening treatmenton an aluminum plate

(Anodization treatment step) A step of anodizing the aluminum platewhich has been subjected to the roughening treatment

(Pore widening treatment step) A step of widening the diameter ofmicropores in the anodized film by bringing the aluminum plate havingthe anodized film obtained in the anodization treatment step intocontact with an acid aqueous solution or an alkali aqueous solution

Hereinafter, the procedures of each step will be described in detail.

—Roughening Treatment Step—

The roughening treatment step is a step of performing a rougheningtreatment including an electrochemical roughening treatment on a surfaceof an aluminum plate. It is preferable that the present step isperformed before the anodization treatment step described below, but maynot be performed in a case where the surface of the aluminum platealready has a preferable surface shape.

The roughening treatment may be carried out by performing only anelectrochemical roughening treatment, but may be performed by combiningan electrochemical roughening treatment and a mechanical rougheningtreatment and/or a chemical roughening treatment.

In a case where the mechanical roughening treatment is combined with theelectrochemical roughening treatment, it is preferable that theelectrochemical roughening treatment is performed after the mechanicalroughening treatment.

It is preferable that the electrochemical roughening treatment isperformed in an aqueous solution mainly containing nitric acid orhydrochloric acid using the direct current or the alternating current.

The method of performing the mechanical roughening treatment is notparticularly limited, and the methods described in JP1975-040047B(JP-S50-040047B) are exemplified.

The chemical roughening treatment is also not particularly limited, andknown methods are exemplified.

It is preferable that a chemical etching treatment described below isperformed after the mechanical roughening treatment.

The chemical etching treatment to be performed after the mechanicalroughening treatment is performed in order to smooth an edge portion ofthe uneven shape of the surface of the aluminum plate, prevent the inkfrom being caught during printing, improve the stain resistance of theprinting plate, and remove unnecessary matter such as abrasive materialparticles remaining on the surface.

Examples of the chemical etching treatment include etching carried outusing an acid and etching carried out using an alkali, and a chemicaletching treatment (hereinafter, also referred to as an “alkali etchingtreatment”) carried out using an alkali aqueous solution is exemplifiedas a particularly excellent method in terms of etching efficiency.

An alkali agent used for the alkali aqueous solution is not particularlylimited, and examples thereof include caustic soda, caustic potash,sodium metasilicate, soda carbonate, soda aluminate, and soda gluconate.

The alkali aqueous solution may contain aluminum ions.

The concentration of the alkali agent in the alkali aqueous solution ispreferably 0.01% by mass or greater, more preferably 3% by mass orgreater, and preferably 30% by mass or less.

In a case where the alkali etching treatment is performed, it ispreferable that the chemical etching treatment (hereinafter, alsoreferred to as a “desmutting treatment”) is performed using an acidicaqueous solution at a low temperature in order to remove a productgenerated due to the alkali etching treatment.

The acid used for the acidic aqueous solution is not particularlylimited, and examples thereof include sulfuric acid, nitric acid, andhydrochloric acid. Further, the temperature of the acidic aqueoussolution is preferably in a range of 20° C. to 80° C.

It is preferable that the roughening treatment step is performedaccording to a method of performing the treatments shown in theembodiment A or the embodiment B in order described below.

Embodiment A

(2) A chemical etching treatment carried out using an alkali aqueoussolution (first alkali etching treatment)

(3) A chemical etching treatment carried out using an acidic aqueoussolution (first desmutting treatment)

(4) An electrochemical roughening treatment carried out using an aqueoussolution that mainly contains nitric acid (first electrochemicalroughening treatment)

(5) A chemical etching treatment carried out using an alkali aqueoussolution (second alkali etching treatment)

(6) A chemical etching treatment carried out using an acidic aqueoussolution (second desmutting treatment)

(7) An electrochemical roughening treatment carried out in an aqueoussolution that mainly contains hydrochloric acid (second electrochemicalroughening treatment)

(8) A chemical etching treatment carried out using an alkali aqueoussolution (third alkali etching treatment)

(9) A chemical etching treatment carried out using an acidic aqueoussolution (third desmutting treatment)

Embodiment B

(10) A chemical etching treatment carried out using an alkali aqueoussolution (fourth alkali etching treatment)

(11) A chemical etching treatment carried out using an acidic aqueoussolution (fourth desmutting treatment)

(12) An electrochemical roughening treatment carried out using anaqueous solution that mainly contains hydrochloric acid (thirdelectrochemical roughening treatment)

(13) A chemical etching treatment carried out using an alkali aqueoussolution (fifth alkali etching treatment)

(14) A chemical etching treatment carried out using an acidic aqueoussolution (fifth desmutting treatment)

The mechanical roughening treatment (1) may be performed before thetreatment (2) of the embodiment A described above or before thetreatment (10) of the embodiment B described above, as necessary.

The amount of the aluminum plate to be dissolved in the first alkalietching treatment and the fourth alkali etching treatment is preferablyin a range of 0.5 g/m² to 30 g/m² and more preferably in a range of 1.0g/m² to 20 g/m².

As the aqueous solution that mainly contains nitric acid used for thefirst electrochemical roughening treatment according to the embodimentA, an aqueous solution used for an electrochemical roughening treatmentcarried out using the direct current or the alternating current isexemplified. For example, an aqueous solution obtained by addingaluminum nitrate, sodium nitrate, or ammonium nitrate to 1 g/L to 100g/L of a nitric acid aqueous solution is exemplified.

As the aqueous solution that mainly contains hydrochloric acid used forthe second electrochemical roughening treatment according to theembodiment A and the third electrochemical roughening treatmentaccording to the embodiment B, an aqueous solution used for anelectrochemical roughening treatment carried out using the directcurrent or the alternating current is exemplified. For example, anaqueous solution obtained by adding 0 g/L to 30 g/L of sulfuric acid toa 1 g/L to 100 g/L hydrochloric acid aqueous solution is exemplified.Further, nitrate ions such as aluminum nitrate, sodium nitrate, andammonium nitrate; and hydrochloride ions such as aluminum chloride,sodium chloride, and ammonium chloride may be further added to thissolution.

As the AC power source waveform of the electrochemical rougheningtreatment, a sine wave, a square wave, a trapezoidal wave, or atriangular wave can be used. The frequency is preferably in a range of0.1 Hz to 250 Hz.

FIG. 1 is a graph showing an example of an alternating waveform currentwaveform diagram used for the electrochemical roughening treatment.

In FIG. 1 , ta represents an anodic reaction time, tc represents acathodic reaction time, tp represents a time taken for the current toreach the peak from 0, Ia represents the peak current on an anode cycleside, and Ic represents the peak current on a cathode cycle side. In thetrapezoidal wave, the time tp taken for the current to reach the peakfrom 0 is preferably in a range of 1 msec to 10 msec. As the preferableconditions for one cycle of the alternating current used for theelectrochemical roughening, a ratio tc/ta of the cathodic reaction timetc to the anodic reaction time ta of the aluminum plate is in a range of1 to 20, a ratio Qc/Qa of an electric quantity Qc in a case of thealuminum plate serving as a cathode to an electric quantity Qa in a caseof the aluminum plate serving as an anode is in a range of 0.3 to 20,and the anodic reaction time ta is in a range of 5 msec to 1000 msec.The current density is preferably in a range of 10 A/dm to 200 A/dm² inboth an anode cycle side Ia and a cathode cycle side Ic of the currentin terms of the peak value of the trapezoidal wave. The value of Ic/Iais preferably in a range of 0.3 to 20. The total electric quantity ofthe aluminum plate used for the anodic reaction in a case where theelectrochemical roughening is completed is preferably in a range of 25C/dm² to 1000 C/dm².

A device illustrated in FIG. 2 can be used for the electrochemicalroughening carried out using the alternating current.

FIG. 2 is a side view illustrating an example of a radial type cell inthe electrochemical roughening treatment carried out using thealternating current.

In FIG. 2 , the reference numeral 50 represents a main electrolyticcell, the reference numeral 51 represents an AC power source, thereference numeral 52 represents a radial drum roller, the referencenumerals 53 a and 53 b represent a main pole, the reference numeral 54represents an electrolytic solution supply port, the reference numeral55 represents an electrolytic solution, the reference numeral 56represents a slit, the reference numeral 57 represents an electrolyticsolution passage, the reference numeral 58 represents an auxiliaryanode, the reference numeral 60 represents an auxiliary anode cell, andthe symbol W represents an aluminum plate. In a case where two or moreelectrolytic cells are used, the electrolysis conditions may be the sameas or different from each other.

The aluminum plate W is wound around the radial drum roller 52 disposedby being immersed in the main electrolytic cell 50 and is electrolyzedby the main poles 53 a and 53 b connected to the AC power source 51 inthe transport process. The electrolytic solution 55 is supplied to theelectrolytic solution passage 57 disposed between the radial drum roller52 and the main pole 53 a and between the radial drum roller 52 and themain pole 53 b through the slit 56 from the electrolytic solution supplyport 54. The aluminum plate W which has been treated in the mainelectrolytic cell 50 is electrolyzed in the auxiliary anode cell 60. Theauxiliary anode 58 is disposed in the auxiliary anode cell 60 so as toface the aluminum plate W and the electrolytic solution 55 is suppliedso as to flow through the space between the auxiliary anode 58 and thealuminum plate W.

From the viewpoint of easily producing a predetermined printing plateprecursor, the amount of the aluminum plate to be dissolved in thesecond alkali etching treatment is preferably 1.0 g/m² or greater andmore preferably in a range of 2.0 g/m² to 10 g/m².

From the viewpoint of easily producing a predetermined printing plateprecursor, the amount of the aluminum plate to be dissolved in the thirdalkali etching treatment and the fourth alkali etching treatment ispreferably 0.01 g/m² to 0.8 g/m² and more preferably in a range of 0.05g/m² to 0.3 g/m².

In the chemical etching treatments (first to fifth desmuttingtreatments) carried out using an acidic aqueous solution, an acidicaqueous solution containing phosphoric acid, nitric acid, sulfuric acid,chromic acid, hydrochloric acid, or mixed acids containing two or moreof these acids is suitably used.

The concentration of the acid in the acidic aqueous solution ispreferably in a range of 0.5% by mass to 60% by mass.

—Anodization Treatment Step—

The procedures of the anodization treatment step are not particularlylimited as long as the above-described micropores are obtained, andknown methods are exemplified.

In the anodization treatment step, an aqueous solution containingsulfuric acid, phosphoric acid, oxalic acid, and the like can be used asan electrolytic cell. For example, the concentration of the sulfuricacid may be in a range of 100 g/L to 300 g/L.

The conditions for the anodization treatment are appropriately setdepending on the electrolytic solution to be used. As an example of theconditions, the liquid temperature is in a range of 5° C. to 70° C.(preferably in a range of 10° C. to 60° C.), the current density is in arange of 0.5 A/dm² to 60 A/dm² (preferably in a range of 5 A/dm² to 60A/dm²), the voltage is in a range of 1 V to 100 V (preferably in a rangeof 5 V to 50 V), the electrolysis time is in a range of 1 second to 100seconds (preferably in a range of 5 seconds to 60 seconds), and thecoating amount is in a range of 0.1 g/m² to 5 g/m² (preferably in arange of 0.2 g/m² to 3 g/m²).

—Pore Widening Treatment—

The pore widening treatment is a treatment (pore diameter wideningtreatment) of widening the diameter (pore diameter) of microporespresent in the anodized film formed by the above-described anodizationtreatment step.

The pore widening treatment can be performed by bringing the aluminumplate obtained in the anodization treatment step into contact with anacid aqueous solution or an alkali aqueous solution. The method ofbringing the aluminum plate into contact with the solution is notparticularly limited, and examples thereof include an immersion methodand a spray method.

The support can be provided with a back coat layer containing an organicpolymer compound described in JP1993-045885A (JP-H05-045885A) and analkoxy compound of silicon described in JP1994-035174A (JP-H06-035174A)on the rear surface thereof as necessary.

<Image Recording Layer>

The planographic printing plate precursor according to the embodiment ofthe present invention includes an image recording layer at the upperside of the support.

It is preferable that the image recording layer contains an infraredabsorbing agent, a polymerization initiator, a polymerizable compound,and a polymer compound. The polymer compound may function as a binderpolymer of the image recording layer or may be present in the imagerecording layer as a polymer compound having a particle shape.

A polymer compound containing styrene and/or acrylonitrile as aconstitutional unit is preferable as the polymer compound.

Examples of the above-described styrene include styrene,p-methylstyrene, p-methoxystyrene, β-methylstyrene,p-methyl-β-methylstyrene, α-methylstyrene, andp-methoxy-β-methylstyrene. Among these, styrene is preferable.

Examples of the above-described acrylonitrile include(meth)acrylonitrile. Among examples, acrylonitrile is preferable.

According to one preferred embodiment of the planographic printing plateprecursor of the present invention, the image recording layer is animage recording layer (hereinafter, also referred to as an “imagerecording layer A”) containing an infrared absorbing agent, apolymerization initiator, a polymerizable compound, and a binderpolymer.

According to another preferred embodiment of the planographic printingplate precursor of the present invention, the image recording layer isan image recording layer (hereinafter, also referred to as an “imagerecording layer B”) containing an infrared absorbing agent, apolymerization initiator, a polymerizable compound, and a polymercompound having a particle shape.

According to a still another preferred embodiment of the planographicprinting plate precursor of the present invention, the image recordinglayer is an image recording layer (hereinafter, also referred to as an“image recording layer C”) containing an infrared absorbing agent andthermoplastic polymer particles.

—Image Recording Layer A—

The image recording layer A contains an infrared absorbing agent, apolymerization initiator, a polymerizable compound, and a binderpolymer. Hereinafter, the constituent components of the image recordinglayer A will be described.

(Infrared Absorbing Agent)

An infrared absorbing agent has a function of converting absorbedinfrared rays into heat and a function of electron transfer and/orenergy transfer to a polymerization initiator described below throughexcitation by infrared rays. As the infrared absorbing agent used in thepresent invention, a coloring agent or a pigment having maximumabsorption at a wavelength of 760 nm to 1200 nm is preferable and thecoloring agent is more preferable.

As the coloring agent, coloring agents described in paragraphs 0082 to0088 of JP2014-104631A can be used.

The average particle diameter of the pigment is preferably in a range of0.01 mm to 1 mm and more preferably in a range of 0.01 mm to 0.5 mm. Aknown dispersion technique used to produce inks or toners can be usedfor dispersion of the pigment. The details are described in “LatestPigment Application Technology” (CMC Publishing Co., Ltd., 1986) and thelike.

The infrared absorbing agent may be used alone or in combination of twoor more kinds thereof.

The content of the infrared absorbing agent is preferably in a range of0.05% by mass to 30% by mass, more preferably in a range of 0.1% by massto 20% by mass, and particularly preferably in a range of 0.2% by massto 10% by mass with respect to total mass of the image recording layer.

(Polymerization Initiator)

The polymerization initiator indicates a compound that initiates andpromotes polymerization of a polymerizable compound. As thepolymerization initiator, a known thermal polymerization initiator, acompound having a bond with small bond dissociation energy, or aphotopolymerization initiator can be used. Specifically, radicalpolymerization initiators described in paragraphs 0092 to 0106 ofJP2014-104631A can be used.

Preferred examples of the compound in the polymerization initiatorsinclude an onium salt. Among these, an iodonium salt and a sulfoniumsalt are particularly preferable. Specific preferred examples of thecompounds in each of the salts are the compounds described in paragraphs0104 to 0106 of JP2014-104631A.

The content of the polymerization initiator is preferably in a range of0.1% by mass to 50% by mass, more preferably in a range of 0.5% by massto 30% by mass, and particularly preferably in a range of 0.8% by massto 20% by mass with respect to the total mass of the image recordinglayer. In a case where the content thereof is in the above-describedrange, improved sensitivity and improved stain resistance of a non-imagearea during printing are obtained.

(Polymerizable Compound)

The polymerizable compound is an addition polymerizable compound havingat least one ethylenically unsaturated bond and is selected fromcompounds having preferably at least one and more preferably two or moreterminal ethylenically unsaturated bonds. These have chemical forms suchas a monomer, a pre-polymer, that is, a dimer, a trimer, an oligomer,and a mixture of these.

Examples of the monomer include unsaturated carboxylic acids (forexample, acrylic acid, methacrylic acid, itaconic acid, crotonic acid,isocrotonic acid, or maleic acid), esters thereof, and amides thereof.Among these, esters of unsaturated carboxylic acids and polyhydricalcohol compounds, and amides of unsaturated carboxylic acids andpolyhydric amine compounds are preferably used. Further, an additionreaction product of unsaturated carboxylic acid ester having anucleophilic substituent such as a hydroxy group, an amino group, or amercapto group or amides with monofunctional or polyfunctionalisocyanates or epoxies, and a dehydration condensation reaction productwith a monofunctional or polyfunctional carboxylic acid are alsosuitably used. Further, an addition reaction product of unsaturatedcarboxylic acid ester having an electrophilic substituent such as anisocyanate group or an epoxy group or amides with monofunctional orpolyfunctional alcohols, amines, and thiols, and a substitution reactionproduct of unsaturated carboxylic acid ester having a releasablesubstituent such as a halogen group or a tosyloxy group or amides withmonofunctional or polyfunctional alcohols, amines, and thiols are alsosuitable.

As another example, a compound group in which unsaturated phosphonicacid, styrene, vinyl ether, or the like is substituted for theunsaturated carboxylic acid can also be used. These are described inJP2006-508380A, JP2002-287344A, JP2008-256850A, JP2001-342222A,JP1997-179296A (JP-H09-179296A), JP1997-179297A (JP-H09-179297A),JP1997-179298A (JP-H09-179298A), JP2004-294935A, JP2006-243493,JP2002-275129A, JP2003-64130A, JP2003-280187A, and JP1998-333321A(JP-H10-333321A).

Specific examples of the monomer of the ester of a polyhydric alcoholcompound and an unsaturated carboxylic acid include acrylic acid estersuch as ethylene glycol diacrylate, 1,3-butanediol diacrylate,tetramethylene glycol diacrylate, propylene glycol diacrylate,trimethylolpropane triacrylate, hexanediol diacrylate, tetraethyleneglycol diacrylate, pentaerythritol tetraacrylate, sorbitol triacrylate,isocyanuric acid ethylene oxide (EO) modified triacrylate, and apolyester acrylate oligomer. Examples of the methacrylic acid esterinclude tetramethylene glycol dimethacrylate, neopentyl glycoldimethacrylate, trimethylolpropane trimethacrylate, ethylene glycoldimethacrylate, pentaerythritol trimethacrylate,bis[p-(3-methacryloxy-2-hydroxypropoxy)phenyl]dimethylmethane, andbis[p-(methacryloxyethoxy)phenyl]dimethylmethane. Further, specificexamples of the monomer of the amide of a polyvalent amine compound andan unsaturated carboxylic acid include methylenebisacrylamide,methylenebismethacrylamide, 1,6-hexamethylenebisacrylamide,1,6-hexamethylenebismethacrylamide, diethylenetriamine trisacrylamide,xylylene bisacrylamide, and xylylene bismethacrylamide.

A urethane-based addition-polymerizable compound produced by theaddition reaction of an isocyanate and a hydroxy group is also suitable,and specific examples thereof include a vinyl urethane compoundcontaining two or more polymerizable vinyl groups in one molecule, whichis obtained by adding a vinyl monomer containing a hydroxy grouprepresented by Formula (b) to a polyisocyanate compound containing twoor more isocyanate groups in one molecule described in JP1973-041708B(JP-S48-041708B).CH₂═C(R_(b4))COOCH₂CH(R_(b5))OH  (b)

However, R_(b4) and R_(b5) represent a hydrogen atom or a methyl group.

Suitable examples of the urethane compound include urethane acrylatesdescribed in JP1976-037193A (JP-S51-037193A), JP1990-032293B(JP-H02-032293B), JP1990-016765B (JP-H02-016765B), JP2003-344997A, andJP2006-065210A, urethane compounds having an ethylene oxide skeletondescribed in JP1983-049860B (JP-S58-049860B), JP1981-017654B(JP-S56-017654B), JP1987-039417B (JP-S62-039417B), JP1987-039418B(JP-S62-039418B), JP2000-250211A, and JP2007-094138A, and urethanecompounds containing a hydrophilic group described in U.S. Pat. No.7,153,632A, JP1996-505958A (JP-H08-505958A), JP2007-293221A, andJP2007-293223A.

Among the examples described above, from the viewpoint that the balancebetween the hydrophilicity related to the developability and thepolymerization ability related to the printing durability is excellent,an isocyanuric acid ethylene oxide-modified acrylate compound and acompound having a urethane bond or a urea bond in a molecule areparticularly preferable.

The polymerizable compound may be used alone or in combination of two ormore kinds thereof.

The details of the structures of these polymerizable compounds, whetherto be used alone or in combination, and the usage method such as theaddition amount can be arbitrarily set according to the finalperformance design of the planographic printing plate precursor.

The content of the polymerizable compound is preferably in a range of 5%by mass to 75% by mass, more preferably in a range of 10% by mass to 70%by mass, and particularly preferably in a range of 15% by mass to 60% bymass with respect to the total mass of the image recording layer.

(Binder Polymer)

A binder polymer can be mainly used to improve the film hardness of theimage recording layer. As the binder polymer, known polymers of therelated art can be used and polymers having coated-film properties arepreferable. Among examples thereof, an acrylic resin, a polyvinyl acetalresin, and a polyurethane resin are preferable.

Suitable examples of the binder polymers include polymers having acrosslinking functional group in the main or a side chain and preferablyin a side chain for improving coated-film hardness of an image area asdescribed in JP2008-195018A. Crosslinking occurs between polymermolecules by a crosslinking group so that curing is promoted.

Preferred examples of the crosslinking functional group include anethylenically unsaturated group such as a (meth)acryl group, a vinylgroup, an allyl group, or a styryl group and an epoxy group, and thecrosslinking functional groups can be introduced into a polymer by apolymer reaction or copolymerization. For example, a reaction between anacrylic polymer having a carboxy group in a side chain or polyurethaneand glycidyl methacrylate or a reaction between a polymer having anepoxy group and an ethylenically unsaturated group-containing carboxylicacid such as methacrylic acid can be used.

The content of the crosslinking group in the binder polymer ispreferably in a range of 0.1 mmol to 10.0 mmol, more preferably in arange of 0.25 mmol to 7.0 mmol, and particularly preferably in a rangeof 0.5 mmol to 5.5 mmol per 1 g of the binder polymer.

Moreover, it is preferable that the binder polymer includes ahydrophilic group. The hydrophilic group contributes to impartingon-press developability to the image recording layer. Particularly, inthe coexistence of a crosslinking group and a hydrophilic group, boththe printing durability and the on-press developability can be achieved.

Examples of the hydrophilic group include a hydroxy group, a carboxygroup, an alkylene oxide structure, an amino group, an ammonium group,an amide group, a sulfo group, and a phosphoric acid group. Among these,an alkylene oxide structure having 1 to 9 alkylene oxide units having 2or 3 carbon atoms is preferable. A monomer having a hydrophilic groupmay be copolymerized in order to provide a hydrophilic group for abinder polymer.

In addition, in order to control the impressing property, a lipophilicgroup such as an alkyl group, an aryl group, an aralkyl group, or analkenyl group can be introduced into the binder polymer. For example, alipophilic group-containing monomer such as methacrylic acid alkyl estermay be copolymerized.

The mass average molecular weight (Mw) of the binder polymer ispreferably 2000 or greater, more preferably 5000 or greater, and stillmore preferably in a range of 10000 to 300000.

The content of the binder polymer is preferably in a range of 3% by massto 90% by mass, more preferably in a range of 5% by mass to 80% by mass,and still more preferably in a range of 10% by mass to 70% by mass withrespect to the total mass of the image recording layer.

As a preferred example of the binder polymer, a polymer compound havinga polyoxyalkylene chain in a side chain is exemplified. In a case wherethe image recording layer contains a polymer compound having apolyoxyalkylene chain in a side chain (hereinafter, also referred to asa POA chain-containing polymer compound), the permeability of dampeningwater is promoted and the on-press developability is improved.

Examples of the resin constituting the main chain of the POAchain-containing polymer compound include an acrylic resin, a polyvinylacetal resin, a polyurethane resin, a polyurea resin, a polyimide resin,a polyamide resin, an epoxy resin, a methacrylic resin, a polystyreneresin, a novolak type phenolic resin, a polyester resin, syntheticrubber, and natural rubber. Among these, an acrylic resin isparticularly preferable.

Further, in the present invention, a “main chain” indicates relativelythe longest bonding chain in a molecule of a polymer compoundconstituting a resin and a “side chain” indicates a molecular chainbranched from the main chain.

The POA chain-containing polymer compound does not substantially containa perfluoroalkyl group. The expression “does not substantially contain aperfluoroalkyl group” means that the mass ratio of a fluorine atompresent as a perfluoroalkyl group in a polymer compound is less than0.5% by mass, and it is preferable that the polymer compound does notcontain a fluorine atom. The mass ratio of the fluorine atom is measuredby an elemental analysis method.

In addition, the “perfluoroalkyl group” is a group in which all hydrogenatoms of the alkyl group are substituted with fluorine atoms.

As alkylene oxide (oxyalkylene) in a polyoxyalkylene chain, alkyleneoxide having 2 to 6 carbon atoms is preferable, ethylene oxide(oxyethylene) or propylene oxide (oxypropylene) is more preferable, andethylene oxide is still more preferable.

The repetition number of the alkylene oxide in a polyoxyalkylene chain,that is, a polyalkylene oxide moiety is preferably in a range of 2 to 50and more preferably in a range of 4 to 25.

In a case where the repetition number of the alkylene oxide is 2 orgreater, the permeability of dampening water is sufficiently improved.Further, from the viewpoint that printing durability is not degraded dueto abrasion, it is preferable that the repetition number thereof is 50or less.

As the polyalkylene oxide moiety, structures described in paragraphs0060 to 0062 of JP2014-104631A are preferable.

The POA chain-containing polymer compound may have crosslinkingproperties in order to improve coated-film hardness of an image area.Examples of the POA chain-containing polymer compounds havingcrosslinking properties are described in paragraphs 0063 to 0072 ofJP2014-104631A.

The proportion of repeating units having a poly(alkylene oxide) moietyin the total repeating units constituting the POA chain-containingpolymer compound is not particularly limited, but is preferably in arange of 0.5% by mole to 80% by mole and more preferably in a range of0.5% by mole to 50% by mole. Specific examples of the POAchain-containing polymer compounds are described in paragraphs 0075 and0076 of JP2014-104631A.

As the POA chain-containing polymer compound, hydrophilic macromolecularcompounds such as polyacrylic acid and polyvinyl alcohol described inJP2008-195018A can be used in combination as necessary. Further, alipophilic polymer compound and a hydrophilic polymer compound can beused in combination.

In addition to the presence of the POA chain-containing polymer compoundin the image recording layer as a binder that plays a role of connectingimage recording layer components with each other, the specific polymercompound may be present in the form of a particle. In a case where thespecific polymer compound is present in the form of a particle, theaverage particle diameter is preferably in a range of 10 nm to 1,000 nm,more preferably in a range of 20 nm to 300 nm, and particularlypreferably in a range of 30 nm to 120 nm.

The content of the POA chain-containing polymer compound is preferablyin a range of 3% by mass to 90% by mass and more preferably in a rangeof 5% by mass to 80% by mass with respect to the total mass of the imagerecording layer. In a case where the content thereof is in theabove-described range, both the permeability of dampening water and theimage formability can be reliably achieved.

Other preferred examples of the binder polymer include a polymercompound (hereinafter, also referred to as a “star type polymercompound”) which has a polymer chain bonded to a nucleus through asulfide bond by using a hexa- to decafunctional polyfunctional thiol asthe nucleus and in which the polymer chain contains a polymerizablegroup. As the star type polymer compound, for example, compoundsdescribed in JP2012-148555A can be preferably used.

Examples of the star type polymer compound include compounds having apolymerizable group such as an ethylenically unsaturated bond in themain chain or in a side chain and preferably in a side chain forimproving coated-film hardness of an image area as described inJP2008-195018A. Crosslinking occurs between polymer molecules by apolymerizable group so that curing is promoted.

Preferred examples of the polymerizable group include an ethylenicallyunsaturated group such as a (meth)acryl group, a vinyl group, an allylgroup, or a styryl group and an epoxy group. Among these, from theviewpoint of polymerization reactivity, a (meth)acryl group, a vinylgroup, or a styryl group is more preferable and a (meth)acryl group isparticularly preferable. These groups can be introduced into a polymerby a polymer reaction or copolymerization. For example, a reactionbetween a polymer having a carboxy group in a side chain thereof andglycidyl methacrylate or a reaction between a polymer having an epoxygroup and ethylenically unsaturated group-containing carboxylic acidsuch as methacrylic acid can be used. These groups may be used incombination.

The content of the crosslinking group in the star type polymer compoundis preferably in a range of 0.1 mmol to 10.0 mmol, more preferably in arange of 0.25 mmol to 7.0 mmol, and particularly preferably in a rangeof 0.5 mmol to 5.5 mmol per 1 g of the star type polymer compound.

Moreover, it is preferable that the star type polymer compound furtherincludes a hydrophilic group. The hydrophilic group contributes toimparting on-press developability to the image recording layer.Particularly, in the coexistence of a polymerizable group and ahydrophilic group, both the printing durability and the developabilitycan be achieved.

Examples of the hydrophilic group include —SO₃M¹, —OH, —CONR¹R² (M¹represents a hydrogen atom, a metal ion, an ammonium ion, or aphosphonium ion, R¹ and R² each independently represent a hydrogen atom,an alkyl group, an alkenyl group, or an aryl group, and R¹ and R² may bebonded to each other to form a ring), —N+R³R⁴R⁵X⁻ (R³ to R⁵ eachindependently represent an alkyl group having 1 to 8 carbon atoms, andX⁻ represents a counter anion), —(CH₂CH₂O)_(n)R, and —(C₃H₆O)_(m)R.

In the above-described formulae, n and m each independently represent aninteger of 1 to 100 and R's each independently represent a hydrogen atomor an alkyl group having 1 to 18 carbon atoms.

Here, in a case where the star type polymer compound is a star typepolymer compound having a polyoxyalkylene chain (for example,—(CH₂CH₂O)_(n)R, and —(C₃H₆O)_(m)R) in a side chain, such a star typepolymer compound is a polymer compound having the above-describedpolyoxyalkylene chain in a side chain.

Among these hydrophilic groups, —CONR¹R², —(CH₂CH₂O)_(n)R, or—(C₃H₆O)_(m)R is preferable, —CONR¹R² or —(CH₂CH₂O)_(n)R is morepreferable, and —(CH₂CH₂O)_(n)R is particularly preferable. In—(CH₂CH₂O)_(n)R, n represents an integer of preferably 1 to 10 andparticularly preferably 1 to 4. Further, R represents more preferably ahydrogen atom or an alkyl group having 1 to 4 carbon atoms andparticularly preferably a hydrogen atom or a methyl group. Thesehydrophilic groups may be used in combination of two or more kindsthereof.

Further, it is preferable that the star type polymer compound does notsubstantially include a carboxylic acid group, a phosphoric acid group,or a phosphonic acid group. Specifically, the amount of these acidgroups is preferably less than 0.1 mmol/g, more preferably less than0.05 mmol/g, and particularly preferably 0.03 mmol/g or less. In a casewhere the amount of these acid groups is less than 0.1 mmol/g,developability is further improved.

In order to control the impressing property, a lipophilic group such asan alkyl group, an aryl group, an aralkyl group, or an alkenyl group canbe introduced to the star type polymer compound. Specifically, alipophilic group-containing monomer such as methacrylic acid alkyl estermay be copolymerized.

Specific examples of the star type polymer compound include compoundsdescribed in paragraphs 0153 to 0157 of JP2014-104631A.

The star type polymer compound can be synthesized, using a known method,by performing radical polymerization on the above-described monomersconstituting a polymer chain in the presence of the above-describedpolyfunctional thiol compound.

The mass average molecular weight (Mw) of the star type polymer compoundis preferably in a range of 5000 to 500000, more preferably in a rangeof 10000 to 250000, and particularly preferably in a range of 20000 to150000. In a case where the weight-average molecular weight thereof isin the above-described range, the on-press developability and theprinting durability are further improved.

The star type polymer compound may be used alone or in combination oftwo or more kinds thereof. Further, the star type polymer compound maybe used in combination with a typical linear binder polymer.

The content of the star type polymer compound is preferably in a rangeof 5% by mass to 95% by mass, more preferably in a range of 10% by massto 90% by mass, and particularly preferably in a range of 15% by mass to85% by mass with respect to the total mass of the image recording layer.

Particularly from the viewpoints of promoting the permeability ofdampening water and improving the on-press developability, star typepolymer compounds described in JP2012-148555A are preferable.

(Other Components)

The image recording layer A can contain other components describedbelow.

(1) Low-Molecular-Weight Hydrophilic Compound

In order to improve the on-press developability without degrading theprinting durability, the image recording layer may contain alow-molecular-weight hydrophilic compound.

Examples of the water-soluble organic compound as thelow-molecular-weight hydrophilic compound include glycols such asethylene glycol, diethylene glycol, triethylene glycol, propyleneglycol, dipropylene glycol, and tripropylene glycol and ether or esterderivatives thereof; polyols such as glycerin, pentaerythritol, andtris(2-hydroxyethyl) isocyanurate; organic amines such astriethanolamine, diethanolamine, and monoethanolamine and salts thereof;organic sulfonic acids such as alkylsulfonic acid, toluenesulfonic acid,and benzenesulfonic acid and salts thereof; organic sulfamic acids suchas alkyl sulfamic acid and salts thereof; organic sulfuric acids such asalkyl sulfuric acid and alkyl ether sulfuric acid and salts thereof,organic phosphonic acids such as phenyl phosphonic acid and saltsthereof, organic carboxylic acids such as tartaric acid, oxalic acid,citric acid, malic acid, lactic acid, gluconic acid, and amino acids andsalts thereof; and betaines.

Among these, it is preferable that the image recording layer contains atleast one compound selected from the group consisting of polyols,organic sulfates, organic sulfonates, and betaines.

Specific examples of the compounds of the organic sulfonates includecompounds described in paragraphs 0026 to 0031 of JP2007-276454A andparagraphs 0020 to 0047 of JP2009-154525A. The salt may be a potassiumsalt or a lithium salt.

Examples of the organic sulfate include compounds described inparagraphs 0034 to 0038 of JP2007-276454A.

As the betaines, compounds having 1 to 5 carbon atoms of hydrocarbonsubstituents to nitrogen atoms are preferable. Specific examples thereofinclude trimethyl ammonium acetate, dimethyl propyl ammonium acetate,3-hydroxy-4-trimethyl ammonio butyrate, 4-(1-pyridinio)butyrate,1-hydroxyethyl-1-imidazolioacetate, trimethyl ammonium methanesulfonate, dimethyl propyl ammonium methane sulfonate,3-trimethylammonio-1-propane sulfonate, and 3-(1-pyridinio)-1-propanesulfonate.

Since the low-molecular-weight hydrophilic compound has a smallstructure of a hydrophobic portion, the hydrophobicity or coated-filmhardness of an image area is not degraded by dampening water permeatinginto an exposed portion (image area) of the image recording layer andthus the ink receptivity or the printing durability of the imagerecording layer can be maintained satisfactorily.

The amount of the low-molecular-weight hydrophilic compounds to be addedto the image recording layer is preferably in a range of 0.5% by mass to20% by mass, more preferably in a range of 1% by mass to 15% by mass,and still more preferably in a range of 2% by mass to 10% by mass withrespect to the total mass of the image recording layer. In a case wherethe amount thereof is in the above-described range, excellent on-pressdevelopability and printing durability can be obtained.

These low-molecular-weight hydrophilic compounds may be used alone or incombination of two or more kinds thereof.

(2) Oil Sensitizer

In order to improve the impressing property, an oil sensitizer such as aphosphonium compound, a nitrogen-containing low-molecular-weightcompound, or an ammonium group-containing polymer can be used for theimage recording layer. Particularly, in a case where a protective layercontains an inorganic layered compound, the above-described compoundsfunction as a surface coating agent of the inorganic layered compoundand prevent a degradation in impressing property due to the inorganiclayered compound during the printing.

The phosphonium compound, the nitrogen-containing low-molecular-weightcompound, and the ammonium group-containing polymer are described inparagraphs 0184 to 0190 of JP2014-104631A in detail.

The content of the oil sensitizer is preferably in a range of 0.01% bymass to 30.0% by mass, more preferably in a range of 0.1% by mass to15.0% by mass, and still more preferably in a range of 1% by mass to 10%by mass with respect to the total mass of the image recording layer.

(3) Other Components

The image recording layer may further contain other components such as asurfactant, a coloring agent, a printing-out agent, a polymerizationinhibitor, a higher fatty acid derivative, a plasticizer, inorganicparticles, an inorganic layered compound, a co-sensitizer, and a chaintransfer agent. Specifically, the compounds and the addition amountsdescribed in paragraphs 0114 to 0159 of JP2008-284817A, paragraphs 0023to 0027 of JP2006-091479A, and paragraph 0060 of US2008/0311520A can bepreferably used.

(Formation of Image Recording Layer A)

The image recording layer A is formed by dispersing or dissolving eachof the above-described required components in a known solvent to preparea coating solution, coating a support with the coating solution directlyor through an undercoat layer using a known method such as a bar coatercoating method, and drying the resultant, as described in paragraphs0142 and 0143 of JP2008-195018A. The coating amount of the imagerecording layer (solid content) on the support to be obtained after thecoating and the drying varies depending on the applications thereof, butis preferably in a range of 0.3 g/m² to 3.0 g/m². In a case where thecoating amount thereof is in the above-described range, excellentsensitivity and excellent film-coating characteristics of the imagerecording layer are obtained.

—Image Recording Layer B—

The image recording layer B contains an infrared absorbing agent, apolymerization initiator, a polymerizable compound, and a polymercompound having a particle shape. Hereinafter, the constituentcomponents of the image recording layer B will be described.

Similarly, the infrared absorbing agent, the polymerization initiator,and the polymerizable compound described in the image recording layer Acan be used as an infrared absorbing agent, a polymerization initiator,and a polymerizable compound in the image recording layer B.

(Polymer Compound Having Particle Shape)

It is preferable that the polymer compound having a particle shape isselected from the group consisting of thermoplastic polymer particles,thermally reactive polymer particles, polymer particles having apolymerizable group, microcapsules encapsulating a hydrophobic compound,and microgels (crosslinked polymer particles). Among these, polymerparticles having a polymerizable group and a microgel are preferable.According to a particularly preferred embodiment, the polymer compoundhaving a particle shape contains at least one ethylenically unsaturatedpolymerizable group. Due to the presence of the polymer compound havinga particle shape, the effects of improving the printing durability of anexposed portion and the on-press developability of an unexposed portioncan be obtained.

Further, it is preferable that the polymer compound having a particleshape is in the form of thermoplastic polymer particles.

Preferred examples of the thermoplastic polymer particles includehydrophobic thermoplastic polymer particles described in ResearchDisclosure No. 33303 on January, 1992, JP1997-123387A (JP-H09-123387A),JP1997-131850A (JP-H09-131850A), JP1997-171249A (JP-H09-171249A),JP1997-171250A (JP-H09-171250A), and EP931647B.

Specific examples of a polymer constituting thermoplastic polymerparticles include homopolymers or copolymers of monomers such asacrylate or methacrylate having structures of ethylene, styrene, vinylchloride, methyl acrylate, ethyl acrylate, methyl methacrylate, ethylmethacrylate, vinylidene chloride, acrylonitrile, vinyl carbazole, andpolyalkylene, and mixtures of these. Among these, polystyrene, styrene,a copolymer containing acrylonitrile, and polymethyl methacrylate aremore preferable. The average particle diameter of the thermoplasticpolymer particles is preferably in a range of 0.01 mm to 3.0 mm.

Examples of the thermally reactive polymer particles include polymerparticles having a thermally reactive group. The thermally reactivepolymer particles are crosslinked by a thermal reaction and havehydrophobic regions formed by a change in functional groups during thecrosslinking.

As the thermally reactive group in polymer particles having a thermallyreactive group, a functional group that performs any reaction may beused as long as a chemical bond is formed, but a polymerizable group ispreferable. Preferred examples of the polymerizable group include anethylenically unsaturated group that performs a radical polymerizationreaction (such as an acryloyl group, a methacryloyl group, a vinylgroup, or an allyl group); a cationic polymerizable group (such as avinyl group, a vinyloxy group, an epoxy group, or an oxetanyl group); anisocyanate group that performs an addition reaction or a block bodythereof, an epoxy group, a vinyloxy group, and a functional group havingactive hydrogen atoms as the reaction partners of these (such as anamino group, a hydroxy group, or a carboxy group); a carboxy group thatperforms a condensation reaction and a hydroxy group or an amino groupas a reaction partner thereof, and an acid anhydride that performs aring opening addition reaction and an amino group or a hydroxy group asa reaction partner thereof.

The microcapsule is a microcapsule in which at least a part ofconstituent components of the image recording layer is encapsulated asdescribed in JP2001-277740A and JP2001-277742A. Further, the constituentcomponents of the image recording layer may be contained in a portionother than the microcapsule. Moreover, a preferred embodiment of theimage recording layer containing the microcapsule is an embodiment inwhich hydrophobic constituent components are encapsulated by amicrocapsule and hydrophilic constituent components are contained by aportion other than the microcapsule.

The microgel (crosslinked polymer particles) may contain a part of theconstituent components of the image recording layer in at least one ofthe surface or the inside thereof. From the viewpoints of image formingsensitivity and printing durability, a reactive microgel having aradical polymerizable group on the surface thereof is particularlypreferable.

The constituent components of the image recording layer can be made intomicrocapsules or microgel particles using a known method.

From the viewpoints of the printing durability, the stain resistance,and the storage stability, it is preferable that the polymer compoundhaving a particle shape is obtained by reacting a polyvalent isocyanatecompound which is an adduct of a polyhydric phenol compound containingtwo or more hydroxy groups in a molecule and isophorone diisocyanatewith a compound containing active hydrogen.

As the polyhydric phenol compound, a compound having a plurality ofbenzene rings containing a phenolic hydroxy group is preferable.

As the compound that contains a compound containing the above-describedactive hydrogen, a polyol compound or a polyamine compound ispreferable, a polyol compound is more preferable, and at least onecompound selected from the group consisting of propylene glycol,glycerin, and trimethylolpropane is still more preferable.

As the resin particles obtained by reacting the compound containingactive hydrogen with the polyvalent isocyanate compound which is anadduct of a polyhydric phenol compound containing two or more hydroxygroups in a molecule and isophorone diisocyanate, polymer particlesdescribed in paragraphs 0032 to 0095 of JP2012-206495A are preferablyexemplified.

Further, from the viewpoints of the printing durability and the solventresistance, it is preferable that the polymer compound having a particleshape has a hydrophobic main chain and both a constitutional unit (i)containing a pendant-cyano group directly bonded to the hydrophobic mainchain and a constitutional unit (ii) containing a pendant group having ahydrophilic polyalkylene oxide segment.

As the hydrophobic main chain, an acrylic resin chain is preferablyexemplified.

Preferred examples of the pendant-cyano group include —[CH₂CH(C≡N)—] and—[CH₂C(CH₃)(C≡N)—].

Further, the constitutional unit having a pendant-cyano group can beeasily derived from an ethylene-based unsaturated monomer such asacrylonitrile or methacrylonitrile or a combination of these.

Further, as the alkylene oxide in the hydrophilic polyalkylene oxidesegment, ethylene oxide or propylene oxide is preferable and ethyleneoxide is more preferable.

The repetition number of alkylene oxide structures in the hydrophilicpolyalkylene oxide segment is preferably in a range of 10 to 100, morepreferably in a range of 25 to 75, and still more preferably in a rangeof 40 to 50.

As the resin particles which have a hydrophobic main chain and both theconstitutional unit (i) containing a pendant-cyano group directly bondedto the hydrophobic main chain and the constitutional unit (ii)containing a pendant group having a hydrophilic polyalkylene oxidesegment, those described in paragraphs 0039 to 0068 of JP2008-503365Aare preferably exemplified.

The average particle diameter of the polymer compound having a particleshape is preferably in a range of 0.01 μm to 3.0 μm, more preferably ina range of 0.03 μm to 2.0 μm, and still more preferably in a range of0.10 μm to 1.0 μm. In a case where the average particle diameter thereofis in the above-described range, excellent resolution and temporalstability are obtained.

The content of the polymer compound having a particle shape ispreferably in a range of 5% by mass to 90% by mass with respect to thetotal mass of the image recording layer.

(Other Components)

The image recording layer B can contain other components described inthe above-described image recording layer A as necessary.

(Formation of Image Recording Layer B)

The image recording layer B can be formed in the same manner as theimage recording layer A described above.

—Image Recording Layer C—

The image recording layer C contains an infrared absorbing agent andthermoplastic polymer particles. Hereinafter, the constituent componentsof the image recording layer C will be described.

(Infrared Absorbing Agent)

As the infrared absorbing agent contained in the image recording layerC, a dye or a pigment having maximum absorption at a wavelength of 760nm to 1200 nm is preferable. A dye is more preferable.

As the dye, commercially available dyes and known dyes described in theliteratures (for example, “Dye Handbook” edited by The Society ofSynthetic Organic Chemistry, Japan, published in 1970, “Near InfraredAbsorbing Dyes” of “Chemical Industry”, p. 45 to 51, published on May,1986, and “Development and Market Trend of Functional Dyes in 1990's”Section 2.3 of Chapter 2 (CMC Publishing Co., Ltd., 1990)) and thepatents can be used. Specific preferred examples thereof includeinfrared absorbing dyes such as an azo dye, a metal complex salt azodye, a pyrazolone azo dye, an anthraquinone dye, a phthalocyanine dye, acarbonium dye, a quinone imine dye, a polymethine dye, and a cyaninedye.

Among these, infrared absorbing dyes having a water-soluble group areparticularly preferable from the viewpoint of addition to the imagerecording layer C.

Specific examples of the infrared absorbing dyes are described below,but the present invention is not limited thereto.

As the pigments, commercially available pigments and pigments describedin Color Index (C. I.) Handbook, “Latest Pigment Handbook” (edited byJapan Pigment Technology Association, 1977), “Latest Pigment ApplicationTechnology” (CMC Publishing Co., Ltd., 1986), and “Printing InkTechnology” (CMC Publishing Co., Ltd., 1984) can be used.

The particle diameter of the pigment is preferably in a range of 0.01 mmto 1 mm and more preferably in a range of 0.01 mm to 0.5 mm. A knowndispersion technique used to produce inks or toners can be used as amethod of dispersing the pigment. The details are described in “LatestPigment Application Technology” (CMC Publishing Co., Ltd., 1986).

The content of the infrared absorbing agent is preferably in a range of0.1% by mass to 30% by mass, more preferably in a range of 0.25% by massto 25% by mass, and particularly preferably in a range of 0.5% by massto 20% by mass with respect to the total mass of the image recordinglayer. In a case where the content thereof is in the above-describedrange, excellent sensitivity is obtained without damaging the filmhardness of the image recording layer.

(Thermoplastic Polymer Particles)

The glass transition temperature (Tg) of the thermoplastic polymerparticles is preferably in a range of 60° C. to 250° C. The Tg of thethermoplastic polymer particles is more preferably in a range of 70° C.to 140° C. and still more preferably in a range of 80° C. to 120° C.

Preferred examples of the thermoplastic polymer particles having a Tg of60° C. or higher include thermoplastic polymer particles described inResearch Disclosure No. 33303 on January, 1992, JP1997-123387A(JP-H09-123387A), JP1997-131850A (JP-H09-131850A), JP1997-171249A(JP-H09-171249A), JP1997-171250A (JP-H09-171250A), and EP931647B.

Specific examples thereof include homopolymers or copolymers formed ofmonomers such as ethylene, styrene, vinyl chloride, methyl acrylate,ethyl acrylate, methyl methacrylate, ethyl methacrylate, vinylidenechloride, acrylonitrile, and vinyl carbazole, and mixtures of these.Among these, polystyrene, styrene, a copolymer containing styrene andacrylonitrile, and polymethyl methacrylate are preferable.

The average particle diameter of the thermoplastic polymer particles ispreferably in a range of 0.005 mm to 2.0 mm from the viewpoints of theresolution and the temporal stability. This value is used as the averageparticle diameter in a case where two or more thermoplastic polymerparticles are mixed with each other. The average particle diameterthereof is more preferably in a range of 0.01 mm to 1.5 mm andparticularly preferably in a range of 0.05 mm to 1.0 mm. Thepolydispersity in a case where two or more thermoplastic polymerparticles are mixed with each other is preferably 0.2 or greater. Theaverage particle diameter and the polydispersity are calculatedaccording to a laser light scattering method.

The thermoplastic polymer particles may be used in combination of two ormore kinds thereof. Specifically, at least two kinds of thermoplasticpolymer particles with different particle sizes or at least two kinds ofthermoplastic polymer particles with different glass transitiontemperatures (Tg) may be exemplified. In a case where two or morethermoplastic polymer particles are used in combination, coated-filmcuring properties of an image area are further improved and printingdurability in a case where a planographic printing plate is obtained isfurther improved.

For example, in a case where thermoplastic polymer particles having thesame particle size are used, voids are present between the thermoplasticpolymer particles to some extent, the curing properties of thecoated-film are not desirable in some cases even in a case where thethermoplastic polymer particles are melted and solidified by imageexposure. Meanwhile, in a case where thermoplastic polymer particleshaving different particle sizes are used, the void volume between thethermoplastic polymer particles can be decreased and thus thecoated-film curing properties of the image area after image exposure canbe improved.

Further, in a case where thermoplastic polymer particles having the sameTg are used, the thermoplastic polymer particles are not sufficientlymelted and solidified and, accordingly, the coated-film curingproperties are not desirable in some cases when an increase intemperature of the image recording layer resulting from image exposureis insufficient. Meanwhile, in a case where thermoplastic polymerparticles having different glass transition temperatures (Tg) are used,the coated-film curing properties of the image area can be improved whenan increase in temperature of the image recording layer resulting fromimage exposure is insufficient.

In a case where two or more thermoplastic polymer particles havingdifferent glass transition temperatures (Tg) are used in combination,the Tg of at least one thermoplastic polymer particle is preferably 60°C. or higher. At this time, a difference in Tg is preferably 10° C. orhigher and more preferably 20° C. or higher. In addition, the content ofthe thermoplastic polymer particles having a Tg of 60° C. or higher ispreferably 70% by mass or greater with respect to the total amount ofall thermoplastic polymer particles.

The thermoplastic polymer particles may include a crosslinking group. Ina case where thermoplastic polymer particles having a crosslinking groupare used, the crosslinking group thermally reacts due to heat generatedby an image-exposed portion so that crosslinking occurs betweenpolymers, coated-film hardness of an image area is improved, and theprinting durability is more excellent. As the crosslinking group, afunctional group, in which any reaction may occur, is not limited aslong as a chemical bond is formed, and examples thereof include anethylenically unsaturated group that performs a polymerization reaction(such as an acryloyl group, a methacryloyl group, a vinyl group, or anallyl group); an isocyanate group that performs an addition reaction ora block body thereof, and a group having active hydrogen atoms as thereaction partners of these (such as an amino group, a hydroxy group, ora carboxyl group); an epoxy group that performs an addition reaction andan amino group, a carboxyl group or a hydroxy group as reaction partnersthereof, a carboxyl group that performs a condensation reaction and ahydroxy group or an amino group; and an acid anhydride that performs aring opening addition reaction and an amino group or a hydroxy group.

Specific examples of the thermoplastic polymer particles having acrosslinking group include thermoplastic polymer particles havingcrosslinking groups such as an acryloyl group, a methacryloyl group, avinyl group, an allyl group, an epoxy group, an amino group, a hydroxygroup, a carboxyl group, an isocyanate group, an acid anhydride, and agroup protecting these. These crosslinking groups may be introduced topolymers in a case of polymerization of particle polymers or may beintroduced using a polymer reaction after polymerization of particlepolymers.

In a case where a crosslinking group is introduced to a polymer in acase of polymerization of polymer particles, it is preferable that amonomer having a crosslinking group may be subjected to an emulsionpolymerization or suspension polymerization. Specific examples of themonomer having a crosslinking group include allyl methacrylate, allylacrylate, vinyl methacrylate, vinyl acrylate, glycidyl methacrylate,glycidyl acrylate, 2-isocyanate ethyl methacrylate or block isocyanateresulting from alcohol thereof, 2-isocyanate ethyl acrylate or blockisocyanate resulting from alcohol thereof, 2-aminoethyl methacrylate,2-aminoethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxyethylacrylate, acrylic acid, methacrylic acid, maleic anhydride, bifunctionalacrylate, and bifunctional methacrylate.

Examples of the polymer reaction used in a case where a crosslinkinggroup is introduced after polymerization of polymer particles includepolymer reactions described in WO96/034316A.

In the thermoplastic polymer particles, polymer particles may react witheach other through a crosslinking group, and the thermoplastic polymerparticles may react with a polymer compound or a low-molecular-weightcompound added to the image recording layer.

The content of the thermoplastic polymer particles is preferably in arange of 50% by mass to 95% by mass, more preferably in a range of 60%by mass to 90% by mass, and particularly preferably in a range of 70% bymass to 85% by mass with respect to the total mass of the imagerecording layer.

(Other Components)

The image recording layer C may contain other components as necessary.

As other components, a surfactant having a polyoxyalkylene group or ahydroxy group is preferably exemplified.

As a surfactant having a polyoxyalkylene group (hereinafter, alsoreferred to as a “POA group”) or a hydroxy group, a surfactant having aPOA group or a hydroxy group can be suitably used, but an anionicsurfactant or a non-ionic surfactant is preferable. Among anionicsurfactants or non-ionic surfactants having a POA group or a hydroxygroup, anionic surfactants or non-ionic surfactants having a POA groupare preferable.

As the POA group, a polyoxyethylene group, a polyoxypropylene group, ora polyoxybutylene group is preferable and a polyoxyethylene group isparticularly preferable.

The average degree of polymerization of an oxyalkylene group ispreferably in a range of 2 to 50 and more preferably in a range of 2 to20.

The number of hydroxy groups is preferably 1 to 10 and more preferablyin a range of 2 to 8. Here, the number of terminal hydroxy groups in theoxyalkylene group is not included in the number of hydroxy groups.

The anionic surfactant having a POA group is not particularly limited,and examples thereof include polyoxyalkylene alkyl ether carboxylates,polyoxyalkylene alkyl sulfosuccinates, polyoxyalkylene alkyl ethersulfuric acid ester salts, alkyl phenoxy polyoxyalkylene propylsulfonates, polyoxyalkylene alkyl sulfophenyl ethers, polyoxyalkylenearyl ether sulfuric acid ester salts, polyoxyalkylene polycyclic phenylether sulfuric acid ester salts, polyoxyalkylene styryl phenyl ethersulfuric acid ester salts, polyoxyalkylene alkyl ether phosphoric acidester salts, polyoxyalkylene alkyl phenyl ether phosphoric acid estersalts, and polyoxyalkylene perfluoroalkyl ether phosphoric acid estersalts.

The anionic surfactant having a hydroxy group is not particularlylimited, and examples thereof include hydroxy carboxylates, hydroxyalkyl ether carboxylates, hydroxy alkane sulfonates, fatty acidmonoglyceride sulfuric acid ester salts, and fatty acid monoglycerideacid ester salts.

The content of the surfactant having a POA group or a hydroxy group ispreferably in a range of 0.05% by mass to 15% by mass and morepreferably in a range of 0.1% by mass to 10% by mass with respect to thetotal mass of the image recording layer.

Hereinafter, specific examples of the surfactant having a POA group or ahydroxy group will be described, but the present invention is notlimited thereto. A surfactant A-12 described below is a trade name ofZonyl FSP and available from Dupont. Further, a surfactant N-11described below is a trade name of Zonyl FSO 100 and available fromDupont. Further, m and n in A-12 each independently represent an integerof 1 or greater.

For the purpose of ensuring coating uniformity of the image recordinglayer, the image recording layer may contain an anionic surfactant thatdoes not have a polyoxyalkylene group or a hydroxy group.

The anionic surfactant is not particularly limited as long as theabove-described purpose is achieved. Among the examples of the anionicsurfactants, alkyl benzene sulfonic acid or a salt thereof, alkylnaphthalene sulfonic acid or a salt thereof, (di)alkyl diphenyl ether(di)sulfonic acid or a salt thereof, or alkyl sulfuric acid ester saltis preferable.

The addition amount of the anionic surfactant that does not have apolyoxyalkylene group or a hydroxy group is preferably in a range of 1%by mass to 50% by mass and more preferably in a range of 1% by mass to30% by mass with respect to the total mass of the surfactant which has apolyoxyalkylene group or a hydroxy group.

Hereinafter, specific examples of the anionic surfactant that does notcontain a polyoxyalkylene group or a hydroxy group will be described,but the present invention is not limited thereto.

Further, for the purpose of ensuring coating uniformity of the imagerecording layer, a non-ionic surfactant that does not have apolyoxyalkylene group or a hydroxy group or a fluorine surfactant may beused. For example, fluorine surfactants described in JP1987-170950A(JP-S62-170950A) are preferably used.

The image recording layer may contain a hydrophilic resin. Preferredexamples of the hydrophilic resin include resins having hydrophilicgroups such as a hydroxy group, a hydroxyethyl group, a hydroxypropylgroup, an amino group, an aminoethyl group, an aminopropyl group, acarboxy group, a carboxylate group, a sulfo group, a sulfonate group,and a phosphoric acid group.

Specific examples of the hydrophilic resin include gum Arabic, casein,gelatin, a starch derivative, carboxy methyl cellulose and sodium saltthereof, cellulose acetate, sodium alginate, vinyl acetate-maleic acidcopolymers, styrene-maleic acid copolymers, polyacrylic acids and saltsof these, polymethacrylic acids and salts of these, a homopolymer and acopolymer of hydroxy ethyl methacrylate, a homopolymer and a copolymerof hydroxy ethyl acrylate, a homopolymer and a copolymer of hydroxypropyl methacrylate, a homopolymer and a copolymer of hydroxy propylacrylate, a homopolymer and a copolymer of hydroxy butyl methacrylate, ahomopolymer and a copolymer of hydroxy butyl acrylate, polyethyleneglycols, hydroxy propylene polymers, polyvinyl alcohols, hydrolyzedpolyvinyl acetate having a degree of hydrolysis of preferably at least60% and more preferably at least 80%, polyvinyl formal, polyvinylbutyral, polyvinylpyrrolidone, a homopolymer and a copolymer ofacrylamide, a homopolymer and a copolymer of methacrylamide, and ahomopolymer and a copolymer of N-methylol acrylamide.

The mass average molecular weight of the hydrophilic resin is preferably2000 or greater from the viewpoint of obtaining sufficient coated-filmhardness or printing durability.

The content of the hydrophilic resin is preferably in a range of 0.5% bymass to 50% by mass and more preferably in a range of 1% by mass to 30%by mass with respect to the total mass of the image recording layer.

The image recording layer may contain inorganic particles other thanthose for forming unevenness described above. Preferred examples of theinorganic particles include silica, alumina, magnesium oxide, titaniumoxide, magnesium carbonate, calcium alginate, and a mixture of these.The inorganic particles can be used for the purpose of improvingcoated-film hardness.

The average particle diameter of the inorganic particles is preferablyin a range of 5 nm to 10 mm and more preferably in a range of 10 nm to 1mm. In a case where the average particle diameter thereof is in theabove described range, the thermoplastic polymer particles are stablydispersed, the film hardness of the image recording layer issufficiently held, and a non-image area with excellent hydrophilicity inwhich printing stain is unlikely to occur can be formed.

The inorganic particles are available as commercially available productssuch as a colloidal silica dispersion and the like.

The content of the inorganic particles is preferably in a range of 1.0%by mass to 70% by mass and more preferably in a range of 5.0% by mass to50% by mass with respect to the total mass of the image recording layer.

The image recording layer may contain a plasticizer in order to provideflexibility for a coated film. Examples of the plasticizer includepolyethylene glycol, tributyl citrate, diethyl phthalate, dibutylphthalate, dihexyl phthalate, dioctyl phthalate, tricresyl phosphate,tributyl phosphate, trioctyl phosphate, and tetrahydrofurfuryl oleate.

The content of the plasticizer is preferably in a range of 0.1% by massto 50% by mass and more preferably in a range of 1% by mass to 30% bymass with respect to the total mass of the image recording layer.

In a case where polymer particles having a thermally reactive functionalgroup (crosslinking group) are used for the image recording layer, acompound that starts or promotes a reaction of the thermally reactivefunctional group (crosslinking group) can be added to the imagerecording layer as necessary. As the compound that starts or promotesthe reaction of the thermally reactive functional group, a compound thatgenerates a radical or a cation by being heated may be exemplified.Examples of the compound include a lophine dimer, a trihalomethylcompound, a peroxide, an azo compound, onium salts including diazoniumsalts and diphenyl iodonium salts, acyl phosphine, and imide sulfonate.The amount of the compound to be added to the image recording layer ispreferably in a range of 1% by mass to 20% by mass and more preferablyin a range of 1% by mass to 10% by mass with respect to the total massof the image recording layer. In a case where the amount thereof is inthe above-described range, the on-press developability is not degradedand excellent effects for starting or promoting a reaction are obtained.

(Formation of Image Recording Layer C)

The image recording layer C is formed by dissolving or dispersing eachof the above-described required components in a suitable solvent toprepare a coating solution, coating a support with the coating solutiondirectly or through an undercoat layer. As the solvent, water or a mixedsolvent of water and an organic solvent is used, and a mixed solvent ofwater and an organic solvent is preferable from the viewpoint of theexcellent surface state after coating. Since the amount of the organicsolvent varies depending on the type of organic solvent, the amountthereof cannot be specified unconditionally, but the amount of theorganic solvent in the mixed solvent is preferably in a range of 5% byvolume to 50% by volume. Here, it is necessary that the amount of theorganic solvent to be used is set such that the thermoplastic polymerparticles are not aggregated. The concentration of solid contents of thecoating solution for an image recording layer is preferably in a rangeof 1% by mass to 50% by mass.

As the organic solvent used as a solvent of the coating solution, awater-soluble organic solvent is preferable. Specific examples thereofinclude an alcohol solvent such as methanol, ethanol, propanol,isopropanol, or 1-methoxy-2-propanol, a ketone solvent such as acetoneor methyl ethyl ketone, a glycol ether solvent such as ethylene glycoldimethyl ether, g-butyrolactone, N,N-dimethylformamide,N,N-dimethylacetamide, tetrahydrofuran, and dimethylsulfoxide.Particularly, an organic solvent having a boiling point of 120° C. orlower and a solubility (amount of a solvent to be dissolved in 100 g ofwater) of 10 g or greater in water is preferable and an organic solventhaving a solubility of 20 g or greater is more preferable.

As a coating method of the coating solution for an image recordinglayer, various methods can be used. Examples of the methods include abar coater coating method, a rotary coating method, a spray coatingmethod, a curtain coating method, a dip coating method, an air knifecoating method, a blade coating method, and a roll coating method. Thecoating amount (solid content) of the image recording layer on thesupport obtained after the coating and the drying varies depending onthe purpose thereof, but is preferably in a range of 0.5 g/m² to 5.0g/m² and more preferably in a range of 0.5 g/m² to 2.0 g/m².

Hereinafter, other constituent elements of the planographic printingplate precursor will be described.

<Undercoat Layer>

The planographic printing plate precursor according to the embodiment ofthe present invention may be provided with an undercoat layer betweenthe image recording layer and the support as necessary. Since bonding ofthe support to the image recording layer is strengthened in the exposedportion and the image recording layer is allowed to be easily peeled offfrom the support in the unexposed portion, the undercoat layercontributes to improvement of the on-press developability withoutdegrading the printing durability. Further, in a case of infrared laserexposure, the undercoat layer functions as a heat insulating layer sothat a degradation in sensitivity due to heat, generated by exposure,being diffused in the support is prevented.

Examples of eth compound used for the undercoat layer include a silanecoupling agent having an ethylenic double bond reaction group, which canbe added and polymerized, described in JP1998-282679A (JP-H10-282679A);and a phosphorous compound having an ethylenic double bond reactiongroup described in JP1990-304441A (JP-H02-304441A). Preferred examplesthereof include polymer compounds having an adsorptive group which canbe adsorbed to the surface of the support, a hydrophilic group, and acrosslinking group, as described in JP2005-125749A and JP2006-188038A.As such a polymer compound, a copolymer of a monomer having anadsorptive group, a monomer having a hydrophilic group, and a monomerhaving a crosslinking group is preferable. Specific examples thereofinclude a copolymer of a monomer having an adsorptive group such as aphenolic hydroxy group, a carboxy group, —PO₃H₂, —OPO₃H₂, —CONHSO₂—,—SO₂NHSO₂—, or —COCH₂COCH₃, a monomer having a hydrophilic group such asa sulfo group, and a monomer having a polymerizable crosslinking groupsuch as a methacryl group or an allyl group. The polymer compound mayinclude a crosslinking group introduced by forming salts between a polarsubstituent of the polymer compound and a compound that includes asubstituent having the opposite charge and an ethylenically unsaturatedbond. Further, monomers other than the monomers described above,preferably hydrophilic monomers may be further copolymerized.

The content of the ethylenically unsaturated bond in the polymercompound for an undercoat layer is preferably in a range of 0.1 to 10.0mmol and more preferably in a range of 2.0 to 5.5 mmol per 1 g of thepolymer compound.

The mass average molecular weight of the polymer compound for anundercoat layer is preferably 5000 or greater and more preferably in arange of 10000 to 300000.

For the purpose of preventing stain over time, the undercoat layer maycontain a chelating agent, a secondary or tertiary amine, apolymerization inhibitor, a compound that includes an amino group or afunctional group having polymerization inhibiting ability and a groupinteracting with the surface of an aluminum support, and the like (forexample, 1,4-diazabicyclo[2.2.2]octane (DABCO),2,3,5,6-tetrahydroxy-p-quinone, chloranil, sulfophthalic acid,hydroxyethyl ethylene diamine triacetic acid, dihydroxyethyl ethylenediamine diacetic acid, or hydroxyethyliminodiacetic acid) in addition tothe compounds for an undercoat layer described above.

The undercoat layer is applied according to a known method. The coatingamount of the undercoat layer after being dried is preferably in a rangeof 0.1 mg/m² to 100 mg/m² and more preferably in a range of 1 mg/m² to30 mg/m².

<Protective Layer>

The planographic printing plate precursor according to the embodiment ofthe present invention includes a protective layer at the upper side ofthe image recording layer. The protective layer has a function ofsuppressing a reaction of inhibiting image formation through oxygenblocking, a function of preventing generation of damage to the imagerecording layer, and a function of preventing ablation in a case ofexposure to a high illuminance laser.

As the protective layer having such functions, a protective layerdescribed in paragraphs 0202 to 0204 of JP2014-104631A can be used.

It is preferable that the protective layer contains a water-solublepolymer. Examples of the water-soluble polymer used in the protectivelayer include polyvinyl alcohol, modified polyvinyl alcohol,polyvinylpyrrolidone, a water-soluble cellulose derivative, polyethyleneglycol, and poly(meth)acrylonitrile.

As the modified polyvinyl alcohol, acid-modified polyvinyl alcoholcontaining a carboxy group or a sulfo group is preferably used. Specificexamples thereof include modified polyvinyl alcohol described inJP2005-250216A and JP2006-259137A.

Among the examples of the water-soluble polymer, polyvinyl alcohol ispreferable, and polyvinyl alcohol having a saponification degree of 50%or greater is more preferable. The saponification degree of polyvinylalcohol is preferably 60% or greater, more preferably 70% or greater,and still more preferably 85% or greater. The upper limit of thesaponification degree is not particularly limited and may be 100% orless.

The saponification degree can be measured according to the methoddescribed in JIS K 6726:1994.

The protective layer is applied according to a known method.

The planographic printing plate precursor can be produced by applying acoating solution of each configuration layer according to a typicalmethod, drying the coating solution, and forming each configurationlayer. The coating solution can be applied according to a die coatingmethod, a dip coating method, an air knife coating method, a curtaincoating method, a roller coating method, a wire bar coating method, agravure coating method, or a slide coating method.

Hereinafter, a key plate precursor which is another aspect of theplanographic printing plate precursor according to the embodiment of thepresent invention will be described.

The key plate precursor is a precursor for preparing a key plate byperforming the same plate-making step (here, image exposure is notrequired) as that for the planographic printing plate precursor, and thekey plate precursor basically does not have photosensitivity. As isknown in the printing industry, a key plate is used by being attached toa plate cylinder in a case where it is necessary to perform printing ona part of the paper surface in two colors or one color in colornewspaper printing (multicolor printing).

[Key Plate Precursor]

The key plate precursor according to the present invention is aplanographic printing plate precursor which includes an aluminumsupport, and a protective layer on the aluminum support, in which thethickness of the protective layer is 0.2 μm or greater, and Expression(1) is satisfied in a case where the Bekk smoothness of the surface ofthe outermost layer at the side where the protective layer is providedis denoted by A seconds.A≤1000  (1)

In regard to the protective layer in the key plate precursor accordingto the present invention, the description on the protective layer in theplanographic printing plate precursor including the image recordinglayer can be applied.

The key plate precursor according to the present invention may include anon-photosensitive layer between the support and the protective layer.Here, the term “non-photosensitive” indicates that the key plateprecursor does not substantially have photosensitivity with respect tolight of a light source used in an image exposure step for a typicalplanographic printing plate precursor that is provided for the printingstep together with the key plate precursor according to the presentinvention. The expression “does not substantially have photosensitivity”indicates that a polymerization reaction does not occur in a range wherethe key plate precursor is typically used.

Examples of the non-photosensitive layer include a non-photosensitivehydrophilic layer and a non-photosensitive resin layer.

The non-photosensitive hydrophilic layer contains a hydrophiliccomponent. The hydrophilic component indicates a component which iscapable of improving the hydrophilicity of the surface in a case ofbeing present on the aluminum support as compared with a case where thecomponent is not present on the aluminum support. Further, thehydrophilicity of the surface can be evaluated based on the contactangle according to a known aerial water drop method. Examples of thehydrophilic component include a compound containing an adsorptive groupthat can be adsorbed on the surface of the aluminum support. Preferredexamples of the adsorptive group that can be adsorbed on the surface ofthe aluminum support include a phenolic hydroxy group, a carboxy group,—PO₃H₂, —OPO₃H₂, —CONHSO₂—, —SO₂NHSO₂—, and —COCH₂COCH₃. The compoundcontaining an adsorptive group that can be adsorbed on the surface ofthe aluminum support may further contain a hydrophilic group. A sulfogroup is preferable as the hydrophilic group. The compound containing anadsorptive group that can be adsorbed on the surface of the aluminumsupport may be a low-molecular-weight compound or a polymer compound. Ina case where the compound is a polymer compound, a copolymer obtainedfrom a monomer containing an adsorptive group that can be adsorbed onthe surface of an aluminum support and a monomer containing ahydrophilic group is preferable.

Specific suitable examples of the compound containing an adsorptivegroup that can be adsorbed on the surface of the aluminum supportinclude a silane coupling agent described in JP1998-282679A(JP-H10-282679) and a phosphorus compound described in JP1990-304441A(JP-H02-304441A). Further, an adsorptive group that can be adsorbed on asurface of an aluminum support and a low-molecular-weight compound orpolymer compound containing a hydrophilic group, described inJP2005-238816A, JP2005-125749A, JP2006-239867A, and JP2006-215263A arealso preferably used.

More preferred examples thereof include a polymer compound containing anadsorptive group that can be adsorbed on a surface of an aluminumsupport and a hydrophilic group, as described in JP2005-125749A andJP2006-188038A.

The content of the compound containing an adsorptive group that can beadsorbed on the surface of the aluminum support is preferably in a rangeof 0.01% to 100% by mass, more preferably in a range of 10% to 100% bymass, and still more preferably in a range of 30% to 100% by mass withrespect to the solid content of the non-photosensitive hydrophiliclayer.

As the hydrophilic component, a surfactant, a phosphoric acid compound,or the like can be used. Components other than the hydrophiliccomponents which can be contained in the non-photosensitive hydrophiliclayer, such as a surfactant, a phosphoric acid compound, and the likewhich can be used as the hydrophilic component, a method of forming thenon-photosensitive hydrophilic layer, and the film thickness of thenon-photosensitive hydrophilic layer are described, for example, inparagraphs [0021] to [0046] of JP2017-065184A.

The key plate precursor according to the present invention may furtherinclude a non-photosensitive resin layer between the non-photosensitivehydrophilic layer and the protective layer. In a case where the keyplate precursor includes a non-photosensitive resin layer, an effect ofimproving the scratch resistance while handling the key plate precursorcan be obtained.

The non-photosensitive resin layer is a layer which can be removed by atleast one of acidic to alkaline dampening water or printing ink on theprinting press.

The non-photosensitive resin layer contains a resin. The resin is mainlyused for the purpose of improving the film hardness of thenon-photosensitive resin layer. As the resin contained in thenon-photosensitive resin layer, a known resin of the related art whichis used as a binder polymer in an image recording layer of a typicalplanographic printing plate precursor can be used, and a resin havingcoated-film properties is preferable. Among examples thereof, an acrylicresin, a polyvinyl acetal resin, and a polyurethane resin arepreferable.

Further, it is preferable that the resin contained in thenon-photosensitive resin layer contains a hydrophilic group. Thehydrophilic group contributes to imparting the on-press developabilityto the non-photosensitive resin layer.

Examples of the hydrophilic group include a hydroxy group, a carboxygroup, an alkylene oxide structure, an amino group, an ammonium group,an amide group, a sulfo group, and a phosphoric acid group. Among these,an alkylene oxide structure having 1 to 9 alkylene oxide units with 2 or3 carbon atoms is preferable. A monomer having a hydrophilic group maybe copolymerized in order to provide a hydrophilic group for a binderpolymer.

The mass average molecular weight (Mw) of the resin contained in thenon-photosensitive resin layer is preferably 2000 or greater, morepreferably 5000 or greater, and still more preferably in a range of10000 to 300000.

The content of the resin contained in the non-photosensitive resin layeris appropriately in a range of 3% to 90% by mass, preferably in a rangeof 5% to 80% by mass, and more preferably in a range of 10% to 70% bymass with respect to the total solid content of the non-photosensitiveresin layer.

Preferred examples of the resin contained in the non-photosensitiveresin layer include a polymer compound having a polyoxyalkylene chain ina side chain. In a case where the non-photosensitive resin layercontains the polymer compound having a polyoxyalkylene chain in a sidechain, the permeability of dampening water is promoted and the on-pressdevelopability is improved.

Preferred other examples of the polymer compound having apolyoxyalkylene chain in a side chain and the resin contained in thenon-photosensitive resin layer, components other than the resin whichcan be contained in the non-photosensitive resin layer, such as alow-molecular-weight hydrophilic compound, a plasticizer, a polymercompound having a fine particle shape, and other components, a method offorming the non-photosensitive resin layer, and the film thickness ofthe non-photosensitive resin layer are described in paragraphs [0084] ofJP2017-065184A.

In the key plate precursor according to the present invention, thearithmetic average height Sa of the surface of the outermost layer atthe side where the protective layer is provided is preferably in a rangeof 0.3 μm to 20 μm. In this manner, as described in the planographicprinting plate precursor including the image recording layer describedabove, the effect of preventing multiple plates from being fed isenhanced, and an excellent property of preventing scratches is obtained.

[Planographic Printing Plate Precursor Laminate]

It is preferable that a planographic printing plate precursor laminateaccording to the embodiment of the present invention is a laminate whichis obtained by laminating a plurality of the planographic printing plateprecursors according to the embodiment of the present invention, inwhich the outermost layer at the side where the image recording layer isprovided and the outermost layer at the side opposite to the side wherethe image recording layer is provided are laminated to be directlybrought into contact with each other.

In a case of the key plate precursor which is another embodiment of theplanographic printing plate precursor according to the presentinvention, the laminate is a key plate precursor laminate obtained bylaminating a plurality of key plate precursors, in which the outermostlayer at the side where the protective layer is provided and theoutermost layer at the side opposite to the side where the protectivelayer is provided are laminated to be directly brought into contact witheach other.

Further, it is preferable that the planographic printing plate precursorlaminate according to the embodiment of the present invention is alaminate obtained by laminating a plurality of planographic printingplate precursors according to the embodiment of the present inventionwithout interposing interleaving paper therebetween.

The number of sheets of laminated precursors is not particularlylimited, but is preferably in a range of 2 sheets to 500 sheets.

The planographic printing plate precursor laminate according to theembodiment of the present invention has an excellent property ofpreventing multiple plates from being fed and an excellent property ofpreventing scratches due to the characteristics of the planographicprinting plate precursor according to the embodiment of the presentinvention and also has a characteristic that accumulation deviation isunlikely to occur.

[Plate-Making Method for Planographic Printing Plate and PlanographicPrinting Method]

A plate-making method for the planographic printing plate according tothe embodiment of the present invention is not particularly limited aslong as the method is a plate-making method for the planographicprinting plate precursor according to the embodiment of the presentinvention, and it is preferable that the method includes a step ofimage-exposing the planographic printing plate precursor according tothe embodiment of the present invention (also referred to as an “imageexposure step”), and a step of supplying at least any one of printingink or dampening water to remove an unexposed portion of the imagerecording layer on the printing press and preparing a planographicprinting plate (also referred to as a “development treatment step”).

The above-described plate-making method is also referred to as an“on-press development system” below.

A planographic printing method according to the embodiment of thepresent invention is a method of plate-making the planographic printingplate using the planographic printing plate precursor according to theembodiment of the present invention and performing printing, and it ispreferable that the method includes a step of image-exposing theplanographic printing plate precursor according to the embodiment of thepresent invention (also referred to as an “image exposure step”), a stepof supplying at least any one of printing ink or dampening water toremove an unexposed portion of the image recording layer on the printingpress to prepare a planographic printing plate (also referred to as a“development treatment step”), and a step of performing printing usingthe obtained planographic printing plate (also referred to as a“printing step”).

Further, in the planographic printing plate precursor according to theembodiment of the present invention, the development treatment step isperformed without performing the image exposure step in a case of thekey plate precursor. In this case, it is preferable that the methodincludes a step of supplying at least any one of printing ink ordampening water to the key printing plate to remove the protective layeron the printing press to prepare a planographic printing plate, and astep of performing printing using the obtained planographic printingplate.

<Image Exposure Step>

The image exposure of the planographic printing plate precursor can beperformed in conformity with an image exposure operation for a typicalplanographic printing plate precursor.

The image exposure is performed by laser exposure through a transparentoriginal picture having a line image, a halftone image, and the like orby laser beam scanning using digital data. The wavelength of a lightsource is preferably in a range of 700 nm to 1400 nm. As the lightsource having a wavelength of 700 nm to 1400 nm, a solid-state laser ora semiconductor laser that radiates infrared rays is preferable. Theoutput of the infrared laser is preferably 100 mW or greater, theexposure time per one pixel is preferably less than 20 microseconds, andthe irradiation energy quantity is preferably in a range of 10 mJ/cm² to300 mJ/cm². For the purpose of reducing the exposure time, it ispreferable to use a multi-beam laser device. The exposure mechanism maybe any of an internal drum system, an external drum system, and a flatbed system. The image exposure can be performed using a plate setteraccording to a usual method.

<Development Treatment Step>

The development treatment can be performed using a typical method. In acase of on-press development, a printing ink receiving portion having alipophilic surface is formed by the image recording layer cured by lightexposure in the exposed portion of the image recording layer in a casewhere at least any one of dampening water or printing ink is supplied tothe image-exposed planographic printing plate precursor on a printingpress. Meanwhile, in an unexposed portion, a non-cured image recordinglayer is dissolved or dispersed by supplied at least any one ofdampening water or printing ink and then removed, a hydrophilic surfaceis exposed to the portion. As the result, dampening water is exposed andadheres to the hydrophilic surface, the printing ink is impressed on theimage recording layer of the exposed region, and then the printing isstarted.

Here, either of dampening water or printing ink may be initiallysupplied to the surface of the planographic printing plate precursor,but it is preferable that dampening water is initially supplied theretoby infiltrating dampening water so that the on-press developability ispromoted.

<Printing Step>

The printing using the obtained planographic printing plate can beperformed according to a typical method. The printing can be performedby supplying desired printing ink and dampening water, as necessary, tothe planographic printing plate.

The amount of the printing ink and dampening water to be supplied is notparticularly limited and may be appropriately set according to thedesired printing.

The method of supplying the printing ink and dampening water to theplanographic printing plate is not particularly limited and a knownmethod can be used.

Further, a planographic printing plate can be prepared from theplanographic printing plate precursor according to the embodiment of thepresent invention even by performing a development treatment using adeveloper by appropriately selecting a binder polymer or the likeserving as a constituent component of the image recording layer.

According to another embodiment of the plate-making method for theplanographic printing plate according to the embodiment of the presentinvention, it is preferable that the method includes a step ofimage-exposing the planographic printing plate precursor according tothe embodiment of the present invention (also referred to as an “imageexposure step”) and a development step of supplying a developer having apH of 2 to 14 to remove the unexposed portion (also referred to as a“developer development step”).

The plate-making method is also referred to as a “developer treatmentsystem”.

According to another embodiment of the planographic printing method ofthe present invention, the method is a method of plate-making for aplanographic printing plate using the planographic printing plateprecursor according to the embodiment of the present invention andperforming printing, and it is preferable that the method includes astep of image-exposing the planographic printing plate precursoraccording to the embodiment of the present invention (also referred toas an “image exposure step”), a development step of supplying adeveloper having a pH of 2 to 14 to remove the unexposed portion (alsoreferred to as a “developer development step”), and a step of performingprinting using the obtained planographic printing plate (hereinafter,also referred to as a “printing step”).

<Image Exposure Step>

The image exposure step in the developer treatment system is the same asthe image exposure step in the on-press development system describedabove.

<Developer Development Step>

Further, a planographic printing plate can be prepared from theplanographic printing plate precursor according to the embodiment of thepresent invention even by performing a development treatment using adeveloper by appropriately selecting a binder polymer or the likeserving as a constituent component of the image recording layer. Thedevelopment treatment using a developer includes a step of supplying adeveloper having a pH of 2 to 12 to remove an unexposed portion of theimage recording layer (also referred to as a simple developmenttreatment). The developer having a pH of 2 to 12 may contain at leastone compound selected from the group consisting of a surfactant and awater-soluble polymer compound.

Further, the embodiment that includes the step of supplying a developerhaving a pH of 2 to 10 to remove an unexposed portion of the imagerecording layer but does not include a water washing step after theunexposed portion removal step is also a preferred embodiment of thesimple development treatment.

The development treatment and a gum liquid treatment step can besimultaneously performed using a method of allowing a developer tocontain a water-soluble polymer compound as necessary.

Accordingly, a post-water washing step is not particularly required, anda drying step can be performed after the development treatment and thegum liquid treatment are performed using one liquid in one step.Therefore, it is preferable that the development treatment using adeveloper is performed according to the method of preparing aplanographic printing plate, including a step of performing adevelopment treatment on the image-exposed planographic printing plateprecursor using a developer having a pH of 2 to 12. After thedevelopment treatment, it is preferable that the drying is performedafter the excessive developer is removed using a squeeze roller.

That is, in the development step of the method of preparing aplanographic printing plate according to the present invention, it ispreferable that the development treatment and the gum liquid treatmentare performed using one liquid in one step.

The expression “the development treatment and the gum liquid treatmentare performed using one liquid and one step” means that the developmenttreatment and the gum liquid treatment are performed in one step usingone liquid without separately performing the development treatment andthe gum liquid treatment as individual steps.

The development treatment can be suitably performed using an automaticdevelopment treatment device provided with developer supply means and arubbing member. As the rubbing member, an automatic developmenttreatment device provided with a rotary brush roll is particularlypreferable.

It is preferable that two or more rotary brush rolls are used. Further,it is preferable that an automatic development treatment device includesmeans for removing the excessive developer, such as a squeeze roller,and drying means such as a hot air device on the rear side of thedevelopment treatment means. Further, the automatic developmenttreatment device may include pre-heating means for performing a heatingtreatment on the image-exposed planographic printing plate precursor onthe front side of the development treatment means.

The treatment carried out using such an automatic development treatmentdevice has an advantage that it is no longer necessary to deal withdevelopment scum derived from an image recording layer (a protectivelayer in a case where the planographic printing plate precursor has aprotective layer) which is generated in a case of a so-called on-pressdevelopment treatment.

In a case where the development is carried out by performing a treatmentmanually, a method of allowing sponge or absorbent cotton to contain anaqueous solution, performing treatment while rubbing the entire platesurface, and drying the aqueous solution after the treatment iscompleted is suitably exemplified as the development treatment method.In a case of an immersion treatment, for example, a method of immersingthe planographic printing plate precursor in a tray, a deep tank, or thelike containing an aqueous solution therein for approximately 60seconds, stirring the solution, and drying the aqueous solution whilerubbing the plate surface with absorbent cotton or sponge is suitablyexemplified.

It is preferable that a device capable of simplifying the structure andthe steps is used in the development treatment.

For example, in the alkali development treatment, a protective layer isremoved by the pre-water washing step, development is performed using analkali developer having a high pH, an alkali is removed by thepost-water washing step, the gum treatment is performed by a gum coatingstep, and drying is performed by a drying step. In the simpledevelopment treatment, development and gum coating can be simultaneouslyperformed using one liquid. Therefore, the post-water washing step andthe gum treatment step can be omitted, and it is preferable that thedrying step is performed as necessary after development and gum coating(gum liquid treatment) are performed using one liquid.

Further, it is preferable that removal of the protective layer,development, and gum coating are simultaneously performed using oneliquid without performing the pre-water washing step. Further, it ispreferable that the excessive developer is removed using a squeezeroller after the development and the gum coating and then drying isperformed.

The development treatment may be performed according to a method ofperforming immersion in a developer once or a method of performingimmersion twice or more times. Among these, a method of performingimmersion in the developer once or twice is preferable.

The immersion may be carried out by passing the exposed planographicprinting plate precursor through a developer tank in which the developeris stored or spraying the developer onto the plate surface of theexposed planographic printing plate precursor using a spray or the like.

Further, the development treatment is performed using one liquid (oneliquid treatment) even in a case where the planographic printing plateprecursor is immersed in the developer twice or more times or in a casewhere the planographic printing plate precursor is immersed, twice ormore times, in the same developer as described above or a developer(fatigue liquid) obtained by dissolving or dispersing components of theimage recording layer using the developer and the development treatment.

In the development treatment, it is preferable to use a rubbing memberand also preferable that a rubbing member such as a brush is installedin a developing bath which removes a non-image area of the imagerecording layer.

The development treatment can be performed by immersing the planographicprinting plate precursor which has been subjected to the exposuretreatment and rubbing the plate surface with brushes or pumping up thetreatment liquid added to an external tank using a pump, spraying thedeveloper from a spray nozzle, and rubbing the plate surface withbrushes at a temperature of preferably 0° C. to 60° C. and morepreferably 15° C. to 40° C., according to a conventional method. Thesedevelopment treatments can be continuously performed plural times. Forexample, the development treatment can be performed by pumping up thedeveloper added to an external tank using a pump, spraying the developerfrom a spray nozzle, rubbing the plate surface with brushes, sprayingthe developer from the spray nozzle again, and rubbing the plate surfacewith the brushes. In a case where the development treatment is performedusing an automatic development treatment device, since the developer isfatigued as the treatment amount increases, it is preferable that thetreatment capability is recovered using a replenisher or a freshdeveloper.

In the development treatment, an automatic development treatment deviceand a gum coater known for a presensitized (PS) plate and computer toplate (CTP) in the related art can also be used. In a case where anautomatic development treatment device is used, for example, any systemfrom among a system of performing the treatment by pumping the developeradded to a developer tank or the developer added to an external tankusing a pump and spraying the developer from a spray nozzle, a system ofperforming the treatment by immersing a printing plate in a tank filledwith the developer and transporting the printing plate using a guideroller in the developer, and a so-called disposable treatment system,which is a system of performing the treatment by supplying thesubstantially unused developer by an amount required for each plate canbe employed. In all systems, it is preferable that a rubbing mechanismusing brushes or a molleton is provided. For example, commerciallyavailable automatic development treatment devices (Clean Out UnitC85/C125, Clean-Out Unit+C85/120, FCF 85V, FCF 125V, FCF News(manufactured by Glunz & Jensen); and Azura CX85, Azura CX125, and AzuraCX150 (manufactured by AGFA GRAPHICS) can be used. In addition, a devicein which a laser exposure portion and an automatic development treatmentdevice portion are integrally incorporated can also be used.

The components and the like of the developer used for the developmentstep will be described in detail.

—pH—

The pH of the developer is preferably in a range of 2 to 12, morepreferably in a range of 5 to 9, and still more preferably in a range of7 to 9. From the viewpoints of the developability and the dispersibilityof the image recording layer, it is advantageous that the value of thepH is set to be higher. However, from the viewpoints of the printabilityand suppression of stain, it is effective that the value of the pH isset to be low.

Here, the pH is a value obtained by performing measurement at 25° C.using a pH meter (model number: HM-31, manufactured by DKK-TOACorporation).

—Surfactant—

The developer may contain a surfactant such as an anionic surfactant, anon-ionic surfactant, a cationic surfactant, or an amphotericsurfactant.

From the viewpoint of blanket stain properties, it is preferable thatthe developer contains at least one selected from the group consistingof an anionic surfactant and an amphoteric surfactant.

Further, it is preferable that the developer contains a non-ionicsurfactant and more preferable that the developer contains at least oneselected from the group consisting of a non-ionic surfactant, an anionicsurfactant, and an amphoteric surfactant.

Preferred examples of the anionic surfactant include compoundsrepresented by Formula (I).R¹—Y¹—X¹  (I)

In Formula (I), R¹ represents an alkyl group, a cycloalkyl group, analkenyl group, an aralkyl group, or an aryl group which may have asubstituent.

As the alkyl group, an alkyl group having 1 to 20 carbon atoms ispreferable, and preferred specific examples thereof include a methylgroup, an ethyl group, a propyl group, an n-butyl group, a sec-butylgroup, a hexyl group, a 2-ethylhexyl group, an octyl group, a decylgroup, a dodecyl group, a hexadecyl group, and a stearyl group.

The cycloalkyl group may be monocyclic or polycyclic. As the monocycliccycloalkyl group, a monocyclic cycloalkyl group having 3 to 8 carbonatoms is preferable, and a cyclopropyl group, a cyclopentyl group, acyclohexyl group, or a cyclooctyl group is more preferable. Preferredexamples of the polycyclic cycloalkyl group include an adamantyl group,a norbornyl group, an isobornyl group, a camphanyl group, adicyclopentyl group, an a-pinel group, and a tricyclodecanyl group.

As the alkenyl group, for example, an alkenyl group having 2 to 20carbon atoms is preferable, and preferred specific examples thereofinclude a vinyl group, an allyl group, a butenyl group, and acyclohexenyl group.

As the aralkyl group, for example, an aralkyl group having 7 to 12carbon atoms is preferable, and preferred specific examples thereofinclude a benzyl group, a phenethyl group, and a naphthylmethyl group.

As the aryl group, for example, an aryl group having 6 to 15 carbonatoms is preferable, and preferred specific examples thereof include aphenyl group, a tolyl group, a dimethylphenyl group, a2,4,6-trimethylphenyl group, a naphthyl group, an anthryl group, and a9,10-dimethoxyanthryl group.

As the substituent, a monovalent nonmetallic atom group excluding ahydrogen atom is used, and preferred examples thereof include a halogenatom (F, Cl, Br, or I), a hydroxy group, an alkoxy group, an aryloxygroup, an acyl group, an amide group, an ester group, an acyloxy group,a carboxy group, a carboxylic acid anion group, and a sulfonic acidanion group.

As specific examples of the alkoxy group in the substituent, a methoxygroup, an ethoxy group, a propyloxy group, an isopropyloxy group, abutyloxy group, a pentyloxy group, a hexyloxy group, a dodecyloxy group,a stearyloxy group, a methoxyethoxy group, a poly(ethyleneoxy) group,and a poly(propyleneoxy) group, respectively having 1 to 40 carbonatoms, are preferable; and these groups respectively having 1 to 20carbon atoms are more preferable. Examples of the aryloxy group includea phenoxy group, a tolyloxy group, a xylyloxy group, a mesityloxy group,a cumenyloxy group, a methoxyphenyloxy group, an ethoxyphenyloxy group,a chlorophenyloxy group, a bromophenyloxy group, and a naphthyloxygroup, respectively having 6 to 18 carbon atoms. Examples of the acylgroup include an acetyl group, a propanoyl group, a butanoyl group, abenzoyl group, and a naphthoyl group, respectively having 2 to 24 carbonatoms. Examples of the amide group include an acetamide group, apropionic acid amide group, a dodecanoic acid amide group, a palmiticacid amide group, a stearic acid amide group, a benzoic acid amidegroup, and a naphthoic acid amide group, respectively having 2 to 24carbon atoms. Examples of the acyloxy group include an acetoxy group, apropanoyloxy group, a benzoyloxy group, and a naphthoyloxy group,respectively having 2 to 20 carbon atoms. Examples of the ester groupinclude a methyl ester group, an ethyl ester group, a propyl estergroup, a hexyl ester group, an octyl ester group, a dodecyl ester group,and a stearyl ester group, respectively having 1 to 24 carbon atoms. Thesubstituent may be formed by combining two or more substituentsdescribed above.

X¹ represents a sulfonate group, a sulfate monoester group, acarboxylate group, or a phosphate group.

Y¹ represents a single bond, —CH₂H_(2n)—,—C_(n-m)H_(2(n-m))OC_(m)H_(2m)—, —O—(CH₂CH₂O)_(n)—,—O—(CH₂CH₂CH₂O)_(n)—, —CO—NH—, or a divalent linking group formed bycombining two or more of these and satisfies the expressions of “n³1”and “n³m³0”.

Among examples of the compound represented by Formula (I), from theviewpoint of scratch and stain resistance, a compound represented byFormula (I-A) or Formula (I-B) is preferable.

In Formulae (I-A) and (I-B), R^(A1) to R^(A10) each independentlyrepresent a hydrogen atom or an alkyl group, nA represents an integer of1 to 3, X^(A1) and X^(A2) each independently represent a sulfonategroup, a sulfate monoester group, a carboxylate group, or a phosphategroup, and Y^(A1) and Y^(A2) each independently represent a single bond,—C_(n)H_(2n)—, —C_(n-m)H_(2(n-m))OC_(m)H_(2m)—, —O—(CH₂CH₂O)_(n)—,—O—(CH₂CH₂CH₂O)_(n)—, —CO—NH—, or a divalent linking group formed bycombining two or more of these and satisfy the inequations of “n≥1” and“n≥m≥0”. The total number of carbon atoms in R^(A1) to R^(A5) or R^(A6)to R^(A10) and Y^(A1) and Y^(A2) is 3 or greater.

The total number of carbon atoms in R^(A1) to R^(A5) and Y^(1A) orR^(A6) to R^(A10) and Y^(A2) in the compound represented by Formula(I-A) or (I-B) is preferably 25 or less and more preferably in a rangeof 4 to 20. The structure of the above-described alkyl group may belinear or branched.

It is preferable that X^(A1) and X^(A2) in the compound represented byFormula (I-A) or (I-B) represent a sulfonate group or a carboxylategroup. Further, the salt structure in X^(A1) and X^(A2) is preferablefrom the viewpoint that the solubility of the alkali metal salt in awater-based solvent is particularly excellent. Among the saltstructures, a sodium salt or a potassium salt is particularlypreferable.

As the compound represented by Formula (I-A) or (I-B), the descriptionin paragraphs 0019 to 0037 of JP2007-206348A can be referred to.

As the anionic surfactant, the compounds described in paragraphs 0023 to0028 of JP2006-065321A can be suitably used.

The amphoteric surfactant used for the developer is not particularlylimited, and examples thereof include an amine oxide-based surfactantsuch as alkyl dimethylamine oxide; a betaine-based surfactant such asalkyl betaine, fatty acid amide propyl betaine, or alkyl imidazole; andan amino acid-based surfactant such as sodium alkylamino fatty acid.

Particularly, alkyl dimethylamine oxide which may have a substituent,alkyl carboxy betaine which may have a substituent, or alkylsulfobetaine which may have a substituent is preferably used. Specificexamples of these include compounds represented by Formula (2) inparagraph 0256 of JP2008-203359A, compounds represented by Formulae (I),(II), and (VI) in paragraph 0028 of JP2008-276166A, and compoundsdescribed in paragraphs 0022 to 0029 of JP2009-047927A.

As the amphoteric ion-based surfactant used for the developer, acompound represented by formula (1) or a compound represented by Formula(2) is preferable.

In Formulae (1) and (2), R¹ and R¹¹ each independently represent analkyl group having 8 to 20 carbon atoms or an alkyl group that containsa linking group having 8 to 20 carbon atoms.

R², R³, R¹², and R¹³ each independently represent a hydrogen atom, analkyl group, or a group containing an ethylene oxide structure.

R⁴ and R¹⁴ each independently represent a single bond or an alkylenegroup.

Further, two groups from among R¹, R², R³, and R⁴ may be bonded to eachother to form a ring structure, and two groups from among R¹¹, R¹², R¹³,and R¹⁴ may be bonded to each other to form a ring structure.

In the compound represented by Formula (1) or the compound representedby Formula (2), the size of the hydrophobic portion increases as thetotal number of carbon atoms increases, and the solubility in awater-based developer is decreased. In this case, the solubility isimproved by mixing an organic solvent such as alcohol that assistsdissolution with water as a dissolution assistant, but the surfactantcannot be dissolved within a proper mixing range in a case where thetotal number of carbon atoms is extremely large. Accordingly, the totalnumber of carbon atoms of R¹ to R⁴ or R¹¹ to R¹⁴ is preferably in arange of 10 to 40 and more preferably in a range of 12 to 30.

The alkyl group containing a linking group represented by R¹ or R¹¹ hasa structure in which a linking group is present between alkyl groups. Inother words, in a case where one linking group is present, the structurecan be represented by “-alkylene group-linking group-alkyl group”.Examples of the linking group include an ester bond, a carbonyl bond,and an amide bond. The structure may have two or more linking groups,but it is preferable that the structure has one linking group, and anamide bond is particularly preferable as the linking group. The totalnumber of carbon atoms of the alkylene group bonded to the linking groupis preferably in a range of 1 to 5. The alkylene group may be linear orbranched, but a linear alkylene group is preferable. The number ofcarbon atoms of the alkyl group bonded to the linking group ispreferably in a range of 3 to 19, and the alkyl group may be linear orbranched, but a linear alkyl group is preferable.

In a case where R² or R¹² represents an alkyl group, the number ofcarbon atoms thereof is preferably in a range of 1 to 5 and particularlypreferably in a range of 1 to 3. The alkyl group may be linear orbranched, but a linear alkyl group is preferable.

In a case where R³ or R¹³ represents an alkyl group, the number ofcarbon atoms thereof is preferably in a range of 1 to 5 and particularlypreferably in a range of 1 to 3. The alkyl group may be linear orbranched, but a linear alkyl group is preferable.

As the group containing an ethylene oxide structure represented by R³ orR¹³, a group represented by —R^(a)(CH₂CH₂O)_(n)R^(b) is exemplified.Here, R^(a) represents a single bond, an oxygen atom, or a divalentorganic group (preferably having 10 or less carbon atoms), R^(b)represents a hydrogen atom or an organic group (preferably having 10 orless carbon atoms), and n represents an integer of 1 to 10.

In a case where R⁴ and R¹⁴ represents an alkylene group, the number ofcarbon atoms thereof is preferably in a range of 1 to 5 and particularlypreferably in a range of 1 to 3. The alkylene group may be linear orbranched, but a linear alkylene group is preferable.

The compound represented by Formula (1) or the compound represented byFormula (2) has preferably an amide bond and more preferably an amidebond as a linking group represented by R¹ or R¹¹.

Representative examples of the compound represented by Formula (1) orthe compound represented by Formula (2) are as follows, but the presentinvention is not limited thereto.

The compound represented by Formula (1) or (2) can be synthesizedaccording to a known method. Further, commercially available productsmay be used. Examples of the commercially available products of thecompound represented by Formula (1) include SOFRAZOLINE LPB, SOFTAZOLINELPB-R, and VISTA MAP (manufactured by Kawaken Fine Chemicals Co., Ltd.),and TAKESAAF C-157L (manufactured by TAKEMOTO OIL & FAT Co., Ltd.).Examples of the commercially available products of the compoundrepresented by Formula (2) include SOFTAZOLINE LAO (manufactured byKawaken Fine Chemicals Co., Ltd.) and AMOGEN AOL (manufactured by DKSCo., Ltd.).

The amphoteric ion-based surfactant may be used alone or in combinationof two or more kinds thereof in a developer.

Examples of non-ionic surfactant include polyoxyethylene alkyl ethers,polyoxyethylene alkyl phenyl ethers, polyoxyethylene polystyryl phenylether, glycerin fatty acid partial esters, sorbitan fatty acid partialesters, pentaerythritol fatty acid partial esters, propylene glycolmonofatty acid ester, sucrose fatty acid partial ester, polyoxyethylenesorbitan fatty acid partial esters, polyoxyethylene sorbitol fatty acidpartial esters, polyethylene glycol fatty acid esters, polyglycerinfatty acid partial esters, polyoxyethylene glycerin fatty acid partialesters, polyoxyethylene diglycerins, fatty acid diethanolamides,N,N-bis-2-hydroxyalkylamines, polyoxyethylene alkylamine,triethanolamine fatty acid ester, trialkylamine oxide, polyoxyethylenealkyl phenyl ethers, andpolyoxyethylene-polyoxypropyleneblockcopolymers.

Further, acetylene glycol-based and acetylene alcohol-based oxyethyleneadducts, and fluorine-based surfactants can also be used. Thesesurfactants can be used in combination of two or more kinds thereof.

Particularly preferred examples of the non-ionic surfactant include anon-ionic aromatic ether-based surfactant represented by Formula (N1).X^(N)—Y^(N)—O-(A¹)_(nB)-(A²)_(mB)-H  (N1)

In the formula, X^(N) represents an aromatic group which may have asubstituent, Y^(N) represents a single bond or an alkylene group having1 to 10 carbon atoms, A¹ and A² are different groups and represent anyof —CH₂CH₂O— or —CH₂CH(CH₃)O—, nB and mB each independently represent aninteger of 0 to 100, where both nB and mB do not represent 0 at the sametime. Further, both nB and mB do not represent 1 at the same time in acase where any of nB or mB represents 0.

In the formula, examples of the aromatic group as X^(N) include a phenylgroup, a naphthyl group, and an anthranyl group. These aromatic groupsmay have a substituent. As the substituent, an organic group having 1 to100 carbon atoms is exemplified. Further, in the formula, the copolymermay be a random or block copolymer in a case where both A and B arepresent.

Specific examples of the organic group having 1 to 100 carbon atomsinclude aliphatic hydrocarbon groups and aromatic hydrocarbon groups,which may be saturated or unsaturated and linear or branched, such as analkyl group, an alkenyl group, an alkynyl group, an aryl group, anaralkyl group, an alkoxy group, an aryloxy group, a N-alkylamino group,a N,N-dialkylamino group, a N-arylamino group, a N,N-diarylamino group,a N-alkyl-N-arylamino group, an acyloxy group, a carbamoyloxy group, aN-alkylcarbamoyloxy group, a N-arylcarbamoyloxy group, aN,N-dialkylcarbamoyloxy group, a N,N-diarylcarbamoyloxy group, aN-alkyl-N-arylcarbamoyloxy group, an acylamino group, a N-alkylacylaminogroup, a N-arylacylamino group, an acyl group, an alkoxycarbonylaminogroup, an alkoxycarbonyl group, an aryloxycarbonyl group, a carbamoylgroup, a N-alkylcarbamoyl group, a N,N-dialkylcarbamoyl group, aN-arylcarbamoyl group, a N,N-diarylcarbamoyl group, aN-alkyl-N-arylcarbamoyl group, a polyoxyalkylene chain, and theabove-described organic group to which a polyoxyalkylene chain isbonded. The alkyl group may be linear or branched.

Further, as the non-ionic surfactants, compounds described in paragraphs0030 to 0040 of JP2006-065321A can also be suitably used.

The cationic surfactant is not particularly limited, and knownsurfactants of the related art can be used. Examples thereof includealkylamine salts, quaternary ammonium salts, alkylimidazolinium salts,polyoxyethylene alkylamine salts, and a polyethylene polyaminederivative.

The surfactant may be used alone or in combination of two or more kindsthereof.

The content of the surfactant is preferably in a range of 1% by mass to25% by mass, more preferably in a range of 2% by mass to 20% by mass,still more preferably in a range of 3% by mass to 15% by mass, andparticularly preferably in a range of 5% by mass to 10% by mass withrespect to the total mass of the developer. In a case where the contentthereof is in the above-described range, the scratch and stainresistance is excellent, the dispersibility of the development scum isexcellent, and the ink impressing property of the planographic printingplate to be obtained is excellent.

—Water-Soluble Polymer Compound—

From the viewpoints of adjusting the viscosity of the developer andprotecting the plate surface of the planographic printing plate to beobtained, the developer may contain a water-soluble polymer compound.

Examples of the water-soluble polymer compound which can be contained inthe developer include soybean polysaccharides, modified starch, arabicgum, dextrin, a fiber derivative (such as carboxymethyl cellulose,carboxyethyl cellulose, or methyl cellulose) and a modified productthereof, pullulan, polyvinyl alcohol and a derivative thereof,polyvinylpyrrolidone, polyacrylamide and an acrylamide copolymer, avinyl methyl ether/maleic anhydride copolymer, a vinyl acetate/maleicanhydride copolymer, and a styrene/maleic anhydride copolymer.

As the soybean polysaccharides, those which have been known in therelated art can be used. For example, SOYAFIBE (trade name, manufacturedby FUJI OIL, CO., LTD.) can be used as a commercially available product,and various grades of products can be used. Preferred examples thereofinclude products in which the viscosity of a 10 mass % aqueous solutionis in a range of 10 mPa·s to 100 mPa·s.

As the modified starch, starch represented by Formula (III) ispreferable. Any of starch such as corn, potato, tapioca, rice, or wheatcan be used as the starch represented by Formula (III). The modificationof the starch can be performed according to a method of decomposing 5 to30 glucose residues per one molecule with an acid or an enzyme andadding oxypropylene to an alkali.

In the formula, the etherification degree (degree of substitution) is ina range of 0.05 to 1.2 per glucose unit, n represents an integer of 3 to30, and m represents an integer of 1 to 3.

Among the examples of the water-soluble polymer compound, soybeanpolysaccharides, modified starch, arabic gum, dextrin, carboxymethylcellulose, and polyvinyl alcohol are particularly preferable.

The water-soluble polymer compound can be used in combination of two ormore kinds thereof.

In a case where the developer contains a water-soluble polymer compound,the content of the water-soluble polymer compound is preferably 3% bymass or less and more preferably 1% by mass or less with respect to thetotal mass of the developer. In a case where the content thereof is inthe above-described range, the viscosity of the developer is moderate,and deposition of development scum and the like on a roller member of anautomatic development treatment device can be suppressed.

—Other Additives—

The developer used in the present invention may contain a wetting agent,a preservative, a chelate compound, an antifoaming agent, an organicacid, an organic solvent, an inorganic acid, and an inorganic salt inaddition to those described above.

Suitable examples of the wetting agent include ethylene glycol,propylene glycol, triethylene glycol, butylene glycol, hexylene glycol,diethylene glycol, dipropylene glycol, glycerin, trimethylolpropane, anddiglycerin. The wetting agent may be used alone or in combination of twoor more kinds thereof. The content of the wetting agent is preferably ina range of 0.1% by mass to 5% by mass with respect to the total mass ofthe developer.

Preferred examples of the preservative include phenol and a derivativethereof, formalin, an imidazole derivative, a sodium dehydroacetate,4-isothiazoline-3-one derivative, benzoisothiazolin-3-one,2-methyl-4-isothiazolin-3-one, a benzotriazole derivative, an amidineguanidine derivative, derivatives of quaternary ammonium salts,pyridine, quinoline, and guanidine, diazine, a triazole derivative,oxazole, an oxazole derivative, nitrobromo alcohol-based2-bromo-2-nitropropane-1,3-diol, 1,1-dibromo-1-nitro-2-ethanol, and1,1-dibromo-1-nitro-2-propanol.

The amount of the preservative to be added is an amount of stablyexhibiting the efficacy for bacteria, molds, yeasts, or the like, and ispreferably in a range of 0.01% by mass to 4% by mass with respect to thetotal mass of the developer even though the amount thereof variesdepending on the type of bacteria, molds, and the yeasts. Further, it ispreferable that the preservative is used in combination of two or morekinds thereof so as to be effective for sterilizing various molds.

Examples of the chelate compound include ethylenediamine tetraaceticacid, a potassium salt thereof, and a sodium salt thereof;diethylenetriamine pentaacetic acid, a potassium salt thereof, and asodium salt thereof, triethylenetetraminehexaacetic acid, a potassiumsalt thereof, and a sodium salt thereof; hydroxyethylethylenediaminetriacetic acid, a potassium salt thereof, and a sodium salt thereof;nitrilotriacetic acid and a sodium salt thereof, and organic phosphonicacids such as 1-hydroxyethane-1,1-diphosphonic acid, a potassium saltthereof, and a sodium salt thereof; and aminotri(methylenephosphonicacid), a potassium salt, and a sodium salt thereof. A salt of an organicamine is effectively used in place of a sodium salt or a potassium saltof a chelating agent.

A chelating agent which is stably present in the composition of thetreatment liquid and does not disturb the printability is preferable asthe chelating agent. The content of the chelating agent is preferably ina range of 0.001% by mass to 1.0% by mass with respect to the total massof the developer.

As the antifoaming agent, a typical silicone-based self-emulsifying typeagent, an emulsifying type agent, or a nonionic compound in which thehydrophilic-lipophilic balance (HLB) is 5 or less can be used. Asilicone antifoaming agent is preferable.

Further, a silicone-based surfactant is regarded as an antifoamingagent.

The content of the antifoaming agent is suitably in a range of 0.001% bymass to 1.0% by mass with respect to the total mass of the developer.

Examples of the organic acid include citric acid, acetic acid, oxalicacid, malonic acid, salicylic acid, caprylic acid, tartaric acid, malicacid, lactic acid, levulinic acid, p-toluenesulfonic acid,xylenesulfonic acid, phytic acid, and organic phosphonic acid. Theorganic acid can be used in the form of an alkali metal salt or ammoniumsalt thereof. The content of the organic acid is preferably in a rangeof 0.01% by mass to 0.5% by mass with respect to the total mass of thedeveloper.

Examples of the organic solvent include aliphatic hydrocarbons (hexane,heptane, “ISOPAR E, H, G” (manufactured by Exxon Chemical Japan Ltd.),and the like), aromatic hydrocarbons (toluene, xylene, and the like),halogenated hydrocarbon (methylene dichloride, ethylene dichloride,trichlene, monochlorobenzene, or the like), and a polar solvent.

Examples of the polar solvent include alcohols (such as methanol,ethanol, propanol, isopropanol, benzyl alcohol, ethylene glycolmonomethyl ether, 2-ethoxyethanol, diethylene glycol monoethyl ether,diethylene glycol monohexyl ether, triethylene glycol monomethyl ether,propylene glycol monoethyl ether, propylene glycol monomethyl ether,polyethylene glycol monomethyl ether, polypropylene glycol,tetraethylene glycol, ethylene glycol monobutyl ether, ethylene glycolmonobenzyl ether, ethylene glycol monophenyl ether, methyl phenylcarbinol, n-amyl alcohol, and methyl amyl alcohol), ketones (such asacetone, methyl ethyl ketone, ethyl butyl ketone, methyl isobutylketone, and cyclohexanone), esters (such as ethyl acetate, propylacetate, butyl acetate, amyl acetate, benzyl acetate, methyl lactate,butyl lactate, ethylene glycol monobutyl acetate, propylene glycolmonomethyl ether acetate, diethylene glycol acetate, diethyl phthalate,and butyl levulinate), and others (such as triethyl phosphate, tricresylphosphate, N-phenylethanolamine, and N-phenyldiethanolamine).

In a case where the organic solvent is insoluble in water, the organicsolvent can be used by being solubilized in water using a surfactant orthe like. In a case where the developer contains an organic solvent,from the viewpoints of safety and inflammability the concentration ofthe solvent in the developer is preferably less than 40% by mass.

Examples the inorganic acid and inorganic salt include phosphoric acid,metaphosphoric acid, primary ammonium phosphate, secondary ammoniumphosphate, primary sodium phosphate, secondary sodium phosphate, primarypotassium phosphate, secondary potassium phosphate, sodiumtripolyphosphate, potassium pyrophosphate, sodium hexametaphosphate,magnesium nitrate, sodium nitrate, potassium nitrate, ammonium nitrate,sodium sulfate, potassium sulfate, ammonium sulfate, sodium sulfite,ammonium sulfite, sodium hydrogen sulfate, and nickel sulfate. Thecontent of the inorganic salt is preferably in a range of 0.01% by massto 0.5% by mass with respect to the total mass of the developer.

The developer is prepared by dissolving or dispersing each of theabove-described components in water as necessary. The concentration ofsolid contents in the developer is preferably in a range of 2% by massto 25% by mass. The developer can be used by preparing a concentrate anddiluting the concentrate with water in a case of use.

It is preferable that the developer is an aqueous developer.

From the viewpoint of the dispersibility of the development scum, it ispreferable that the developer contains an alcohol compound.

Examples of the alcohol compound include methanol, ethanol, propanol,isopropanol, and benzyl alcohol. Among these, benzyl alcohol ispreferable.

From the viewpoint of the dispersibility of the development scum, thecontent of the alcohol compound is preferably in a range of 0.01% bymass to 5% by mass, more preferably in a range of 0.1% by mass to 2% bymass, and particularly preferably in a range of 0.2% by mass to 1% bymass with respect to the total mass of the developer.

<Printing Step>

The printing method of using the planographic printing plate obtainedaccording to the developer treatment system is not particularly limited,and the printing may be performed using a known method.

Examples thereof include a method of performing printing by supplyingink and dampening water as necessary to the planographic printing plate.

The planographic printing method according to the embodiment of thepresent invention may include known steps other than the above-describedsteps. Examples of other steps include a plate inspection step ofconfirming the orientation or position of the planographic printingplate precursor before each step and a confirmation step of confirmingthe printed image after the development treatment step.

EXAMPLES

Hereinafter, the present invention will be described in detail withreference to examples, but the present invention is not limited thereto.In the examples, “%” and “part” respectively indicate “% by mass” and“part by mass” unless otherwise specified. In a polymer compound, themolecular weight indicates the mass average molecular weight (Mw) andthe proportion of constitutional repeating units indicates the molepercentage unless otherwise specified. Further, the mass averagemolecular weight (Mw) is a value in terms of polystyrene obtained byperforming measurement using a gel permeation chromatography (GPC)method.

Examples 1 to 45 and Comparative Examples 1 to 6

<Preparation of Support 1>

The following treatments (A-a) to (A-g) were performed on an aluminumplate [aluminum alloy plate] formed of a material 1S having a thicknessof 0.3 mm, thereby preparing a support 1. Moreover, during all treatmentsteps, a water washing treatment was performed, and liquid cutting wasperformed using a nip roller after the water washing treatment.

(A-a) Alkali Etching Treatment

The aluminum plate was subjected to an etching treatment by spraying acaustic soda aqueous solution having a caustic soda concentration of 26%by mass and an aluminum ion concentration of 6.5% by mass, to thealuminum plate using a spray at a temperature of 70° C. The amount ofaluminum dissolved in the surface to be subsequently subjected to anelectrochemical roughening treatment was 5 g/m².

(A-b) Desmutting Treatment Using Acidic Aqueous Solution

A desmutting treatment was performed by spraying, as an acidic aqueoussolution, an aqueous solution having a sulfuric acid concentration of150 g/L at a liquid temperature of 30° C., to the aluminum plate using aspray for 3 seconds.

(A-c) Electrochemical Roughening Treatment Using Hydrochloric AcidAqueous Solution

An electrochemical roughening treatment was performed using the ACcurrent and an electrolytic solution having a hydrochloric acidconcentration of 14 g/L, an aluminum ion concentration of 13 g/L, and asulfuric acid concentration of 3 g/L. The liquid temperature of theelectrolytic solution was 30° C. The aluminum ion concentration wasadjusted by adding aluminum chloride.

The waveform of the AC current was a sine wave in which the positive andnegative waveforms were symmetrical, the frequency was 50 Hz, the ratiobetween the anodic reaction time and the cathodic reaction time in onecycle of the AC current was 1:1, and the current density was 75 A/dm² interms of the peak current value of the AC current waveform. Further, thetotal electric quantity of the aluminum plate used for the anodicreaction was 450 C/dm², and the electrolytic treatment was performedfour times at energization intervals of 4 seconds for each of theelectric quantity of 112.5 C/dm². A carbon electrode was used as acounter electrode of the aluminum plate.

(A-d) Alkali Etching Treatment

The aluminum plate was subjected to an etching treatment by spraying acaustic soda aqueous solution having a caustic soda concentration of 5%by mass and an aluminum ion concentration of 0.5% by mass, to thealuminum plate using a spray at a temperature of 45° C. The amount ofaluminum dissolved in the surface after being subjected to anelectrochemical roughening treatment was 0.2 g/m².

(A-e) Desmutting Treatment Using Acidic Aqueous Solution

A desmutting treatment was performed by spraying, as an acidic aqueoussolution, a waste liquid (an aqueous solution having a sulfuric acidconcentration of 170 g/L and an aluminum ion concentration of 5 g/L)generated in the anodization treatment step at a liquid temperature of30° C., to the aluminum plate using a spray for 3 seconds.

(A-f) Anodization Treatment

An anodization treatment was performed by an anodization device having astructure illustrated in FIG. 3 using DC electrolysis. The anodizationtreatment was performed using a 170 g/L sulfuric acid aqueous solutionas an electrolytic solution under conditions of a liquid temperature of50° C. and a current density of 30 A/dm² to form an anodized film havinga coating amount of 2.4 g/m².

In an anodization treatment device 410 illustrated in FIG. 3 , analuminum plate 416 was transported as indicated by the arrow in FIG. 3 .The aluminum plate 416 was positively (+) charged by a power supplyelectrode 420 in a power supply tank 412 in which an electrolyticsolution 418 was stored. Further, the aluminum plate 416 was transportedupward by a roller 422 in the power supply tank 412, redirected downwardby a nip roller 424, transported toward an electrolytic treatment tank414 in which an electrolytic solution 426 was stored, and redirected tothe horizontal direction by a roller 428. Next, the aluminum plate 416was negatively (−) charged by an electrolytic electrode 430 so that ananodized film was formed on the surface thereof, and the aluminum plate416 coming out of the electrolytic treatment tank 414 was transported tothe next step. In the anodization treatment device 410, a directionchanging unit is formed of the roller 422, the nip roller 424, and theroller 428. The aluminum plate 416 was transported in a mountain shapeand an inverted U shape by the rollers 422, 424, and 428 in aninter-tank portion between the power supply tank 412 and theelectrolytic treatment tank 414. The power supply electrode 420 and theelectrolytic electrode 430 are connected to a DC power source 434.

(A-g) Pore Widening Treatment

The aluminum plate after being subjected to the anodization treatmentwas subjected to a pore widening treatment by being immersed in acaustic soda aqueous solution having a caustic soda concentration of 5%by mass and an aluminum ion concentration of 0.5% by mass at atemperature of 40° C. for 3 seconds. Thereafter, the aluminum plate waswashed with water using a spray. The average diameter of the microporeswas 30 nm.

<Preparation of Support 2>

The following treatments (a) to (m) were performed on an aluminum alloyplate having a thickness of 0.3 mm with the composition listed in Table1, thereby preparing a support 2. Moreover, during all treatment steps,a water washing treatment was performed, and liquid cutting wasperformed using a nip roller after the water washing treatment.

TABLE 1 Composition (% by mass) Si Fe Cu Mn Mg Zn Ti Al 0.085 0.3030.037 0 0 0 0.018 Re- main- der

(a) Mechanical Roughening Treatment (Brush Grain Method)

While supplying a suspension of pumice (specific gravity of 1.1 g/cm³)to the surface of the aluminum plate as a polishing slurry liquid, amechanical roughening treatment was performed using rotating bundlebristle brushes.

The mechanical roughening treatment was performed under conditions inwhich the median diameter of a polishing material pumice was 30 mm, thenumber of the bundle bristle brushes was four, and the rotation speed ofthe bundle bristle brushes was set to 250 rpm. The material of thebundle bristle brushes was nylon 6.10, the diameter of the brushbristles was 0.3 mm, and the bristle length was 50 mm. The bundlebristle brushes were produced by implanting bristles densely into theholes in a stainless steel cylinder having a diameter of 300 mm. Thedistance between two support rollers (with a diameter of 200 mm) of thelower portion of the bundle bristle brush was 300 mm. The bundle bristlebrushes were pressed until the load of a driving motor for rotating thebrushes became 10 kW plus with respect to the load before the bundlebristle brushes were pressed against the aluminum plate. The rotationdirection of the bundle bristle brushes was the same as the movingdirection of the aluminum plate.

(b) Alkali Etching Treatment

The aluminum plate was subjected to an etching treatment by spraying acaustic soda aqueous solution having a caustic soda concentration of 26%by mass and an aluminum ion concentration of 6.5% by mass, to thealuminum plate using a spray tube at a temperature of 70° C. The amountof aluminum dissolved was 10 g/m².

(c) Desmutting Treatment in Acidic Aqueous Solution

Next, a desmutting treatment was performed in a nitric acid aqueoussolution. As the nitric acid aqueous solution used in the desmuttingtreatment, a nitric acid electrolytic solution used for electrochemicalroughening in the subsequent step was used. The liquid temperature was35° C. The desmutting treatment was performed for 3 seconds by sprayingthe desmutting liquid using a spray.

(d) Electrochemical Roughening Treatment

An electrochemical roughening treatment was continuously performed usingan AC voltage of 60 Hz. An electrolytic solution which had been adjustedto have an aluminum ion concentration of 4.5 g/L by adding aluminumnitrate to an aqueous solution having a nitric acid concentration of10.4 g/L at a temperature of 35° C. was used as the electrolyticsolution. Using a trapezoidal rectangular waveform AC having a time tp,until the current value reached a peak from zero, of 0.8 msec and a dutyratio of 1:1 as the AC power source waveform, the electrochemicalroughening treatment was performed using a carbon electrode as a counterelectrode. As an auxiliary anode, ferrite was used. The current densitywas 30 A/dm² in terms of the peak current value, and 5% of the currentfrom the power source was separately flowed to the auxiliary anode. Theelectric quantity was 185 C/dm² as the total electric quantity duringthe anodization of the aluminum plate.

(e) Alkali Etching Treatment

The aluminum plate was subjected to an etching treatment by spraying acaustic soda aqueous solution having a caustic soda concentration of 5%by mass and an aluminum ion concentration of 0.5% by mass using a spraytube at a temperature of 50° C. The amount of aluminum dissolved was 0.5g/m².

(f) Desmutting Treatment in Acidic Aqueous Solution

A desmutting treatment was performed by spraying, as an acidic aqueoussolution, a sulfuric acid aqueous solution having a sulfuric acidconcentration of 170 g/L and an aluminum ion concentration of 5 g/L at aliquid temperature of 60° C., to the aluminum plate using a spray for 3seconds.

(g) Electrochemical Roughening Treatment

An electrochemical roughening treatment was continuously performed usingan AC voltage of 60 Hz. An electrolytic solution which had been adjustedto have an aluminum ion concentration of 4.5 g/L by adding aluminumchloride to an aqueous solution having a hydrochloric acid concentrationof 6.2 g/L at a liquid temperature of 35° C. was used. Using atrapezoidal rectangular waveform AC having a time tp, until the currentvalue reached a peak from zero, of 0.8 msec and a duty ratio of 1:1 asthe AC power source waveform, the electrochemical roughening treatmentwas performed using a carbon electrode as a counter electrode. As anauxiliary anode, ferrite was used. The current density was 25 A/dm² interms of the peak current value, and the electric quantity in thehydrochloric acid electrolysis was 63 C/dm² as the total electricquantity during the anodization of the aluminum plate.

(h) Alkali Etching Treatment

The aluminum plate was subjected to an etching treatment by spraying acaustic soda aqueous solution having a caustic soda concentration of 5%by mass and an aluminum ion concentration of 0.5% by mass using a spraytube at a temperature of 50° C. The amount of aluminum dissolved was 0.1g/m².

(i) Desmutting Treatment in Acidic Aqueous Solution

A desmutting treatment was performed by spraying, as an acidic aqueoussolution, a sulfuric acid aqueous solution (an aqueous solution having asulfuric acid concentration of 170 g/L and an aluminum ion concentrationof 5 g/L) used in the anodization treatment step at a liquid temperatureof 35° C., to the aluminum plate using a spray for 3 seconds.

(j) First Anodization Treatment

A first stage of an anodization treatment was performed with ananodization device using DC electrolysis. An anodized film having apredetermined film thickness was formed by performing an anodizationtreatment under conditions listed in Table 2. An aqueous solutioncontaining components listed in Table 2 was used as the electrolyticsolution. In Tables 2 to 4, the “component concentration” indicates theconcentration (g/L) of each component described in the section of“liquid component”.

TABLE 2 First anodization treatment Concen- Type tration of Temper-Current Film of Liquid component ature density Time thickness liquidcomponent (g/L) (° C.) (A/dm2) (s) (nm) Sulfuric H₂SO₄/Al 170/5 55 900.40 110 acid

(k) Second Anodization Treatment

A second stage of an anodization treatment was performed with ananodization device using DC electrolysis. An anodized film having apredetermined film thickness was formed by performing an anodizationtreatment under conditions listed in Table 3. An aqueous solutioncontaining components listed in Table 3 was used as the electrolyticsolution.

TABLE 3 Second anodization treatment Concen- Type tration of Temper-Current Film of Liquid component ature density Time thickness liquidcomponent (g/L) (° C.) (A/dm2) (s) (nm) Sulfuric H₂SO₄/Al 170/5 54 15 13900 acid

(l) Third Anodization Treatment

A third stage of an anodization treatment was performed with ananodization device using DC electrolysis. An anodized film having apredetermined film thickness was formed by performing an anodizationtreatment under conditions listed in Table 4. An aqueous solutioncontaining components listed in Table 4 was used as the electrolyticsolution.

TABLE 4 Third anodization treatment Concen- Type tration of Temper-Current Film of Liquid component ature density Time thickness liquidcomponent (g/L) (° C.) (A/dm2) (s) (nm) Sulfuric H₂SO₄/Al 170/5 54 500.4 100 acid

(m) Hydrophilization Treatment

In order to ensure hydrophilicity of a non-image area, the non-imagearea was subjected to a silicate treatment by being immersed using 2.5%by mass of a No. 3 sodium silicate aqueous solution at 50° C. for 7seconds. The adhesion amount of Si was 8.5 mg/m².

The average diameter (average diameter of surface layers) oflarge-diameter pores in the surface of the anodized film havingmicropores obtained in the above-described manner, the average diameter(average diameter of bottom portions) of the large-diameter pores in acommunication position, the average diameter (diameter of small-diameterpores) of small-diameter pores in the communication position, theaverage depth of the large-diameter pores and the small-diameter pores,the thickness (thickness of barrier layer) of the anodized film from thebottom portions of the small-diameter pores to the surface of thealuminum plate, and the density of the small-diameter pores are listedin Tables 5 and 6. The small-diameter pores include first small-diameterpores and second small-diameter pores with depths different from eachother and small-diameter pores which are deeper than the other arereferred to as the first small-diameter pores.

TABLE 5 Micropores Large-diameter pores Average Average Average Averagedepth/ depth/ diameter diameter Average Average of surface of bottomAverage diameter of diameter of layers portions depth surface bottom(nm) (nm) (nm) layers portions Shape 12 25 98 8.2 3.9 Reversed taperedshape

TABLE 6 Micropores Small-diameter pores Ratio Density of Average MinimumDensity of Increase (average thickness Average Average communicationthickness of thickness of micropores magnification of surface diameterdepth portion barrier layers barrier layer (particles/ of surfacelayers/diameter of (nm) (nm) (particles/μm²) (nm) (nm) μm²) areasmall-diameter pores) 9.8 888, 800 17 16 500 4.0 1.22 968  (650)

In Table 6, the average value and the minimum value are shown as thebarrier layer thickness. The average value is obtained by measuring 50thicknesses of the anodized film from the bottom portions of the firstsmall-diameter pores to the surface of the aluminum plate andarithmetically averaging the values.

The average diameter of micropores (average diameter of thelarge-diameter pores and the small-diameter pores) is a value obtainedby observing 4 sheets (N=4) of the surfaces of the large-diameter poresand the surfaces of the small-diameter pores using a field emissionscanning electron microscope (FE-SEM) at a magnification of 150000,measuring the diameters of micropores (the large-diameter pores and thesmall-diameter pores) present in a range of 400×600 nm² in the obtainedfour sheets of images, and averaging the values. Further, in a casewhere the depth of the large-diameter pores is deep and the diameter ofthe small-diameter pores is unlikely to be measured, the upper portionof the anodized film is cut and then various kinds of diameters areacquired.

The average depth of the large-diameter pores is a value obtained byobserving the cross section of the support (anodized film) using FE-TEMat a magnification of 500000, measuring 60 cases (N=60) of distancesfrom the surface of an arbitrary micropore to the communication positionin the obtained image, and averaging the values. Further, the averagedepth of the small-diameter pores is a value obtained by observing thecross section of the support (anodized film) using FE-SEM (at amagnification of 50000), measuring 25 cases of depths of arbitrarymicropores in the obtained image, and averaging the values.

The “density of the communication portion” indicates the density of thesmall-diameter pores of the cross section of the anodized film in thecommunication position. The “increase magnification of the surface area”indicates the value calculated based on the following Equation (A).Increase magnification of surface area=1+pore density×((π×(averagediameter of surface layers/2+average diameter of bottomportions/2)×((average diameter of bottom portions/2−average diameter ofsurface layers/2)²+depth A²)^(1/2)+π×(average diameter of bottomportions/2)²−π×(average diameter of surface layers/2)²))  Equation (A)

In the column of the “average depth (nm)” of the small-diameter pores,the average depth of the second small-diameter pores is shown on theleft side and the average depth of the first small-diameter pores isshown on the right side. In the column of the “density of communicationportion” of the small-diameter pores, the density of the firstsmall-diameter pores is shown in the parentheses together with thedensity of the communication portion of the small-diameter pores.

In addition, the average diameter of the first small-diameter porespositioning from the bottom portions of the second small-diameter poresto the bottom portions of the first small-diameter pores wasapproximately 12 nm.

<Preparation of Support 3>

A support 3 was prepared in the same manner as in the preparation of thesupport 1 except that the temperature of the pore widening treatment(A-g) was changed to 28° C. in the preparation of the support 1. Theaverage diameter of the micropores was 13 nm.

<Preparation of Support 4>

A support 4 was prepared in the same manner as in the preparation of thesupport 1 except that the liquid temperature in the anodizationtreatment (A-f) was changed to 15° C., the current density was changedto 60 A/dm², and the time of the pore widening treatment (A-g) waschanged to 15 seconds in the preparation of the support 1. The averagediameter of the micropores was 100 nm.

<Preparation of Support 5>

The following treatments (B-a) to (B-h) were performed on an aluminumplate formed of a material 1S having a thickness of 0.3 mm, therebypreparing a support 5. Moreover, during all treatment steps, a waterwashing treatment was performed, and liquid cutting was performed usinga nip roller after the water washing treatment.

(B-a) Alkali Etching Treatment

The aluminum plate was subjected to an etching treatment by spraying acaustic soda aqueous solution having a caustic soda concentration of 26%by mass and an aluminum ion concentration of 6.5% by mass, to thealuminum plate using a spray at a temperature of 70° C. The amount ofaluminum dissolved in the surface to be subsequently subjected to anelectrochemical roughening treatment was 5 g/m².

(B-b) Desmutting Treatment Using Acidic Aqueous Solution

A desmutting treatment was performed by spraying, as an acidic aqueoussolution, an aqueous solution having a sulfuric acid concentration of150 g/L at a liquid temperature of 30° C., to the aluminum plate using aspray for 3 seconds.

(B-c) Electrochemical Roughening Treatment Using Hydrochloric AcidAqueous Solution.

An electrochemical roughening treatment was performed using the ACcurrent and an electrolytic solution having a hydrochloric acidconcentration of 14 g/L, an aluminum ion concentration of 13 g/L, and asulfuric acid concentration of 3 g/L. The liquid temperature of theelectrolytic solution was 30° C. The aluminum ion concentration wasadjusted by adding aluminum chloride.

The waveform of the AC current was a sine wave in which the positive andnegative waveforms were symmetrical, the frequency was 50 Hz, the ratiobetween the anodic reaction time and the cathodic reaction time in onecycle of the AC current was 1:1, and the current density was 75 A/dm² interms of the peak current value of the AC current waveform. Further, thetotal electric quantity of the aluminum plate used for the anodicreaction was 450 C/dm², and the electrolytic treatment was performedfour times at energization intervals of 4 seconds for each of theelectric quantity of 112.5 C/dm². A carbon electrode was used as acounter electrode of the aluminum plate.

(B-d) Alkali Etching Treatment

The aluminum plate was subjected to an etching treatment by spraying acaustic soda aqueous solution having a caustic soda concentration of 5%by mass and an aluminum ion concentration of 0.5% by mass, to thealuminum plate using a spray at a temperature of 45° C. The amount ofaluminum dissolved in the surface after being subjected to anelectrochemical roughening treatment was 0.2 g/m².

(B-e) Desmutting Treatment Using Acidic Aqueous Solution

A desmutting treatment was performed by spraying, as an acidic aqueoussolution, a waste liquid (an aqueous solution having a sulfuric acidconcentration of 170 g/L and an aluminum ion concentration of 5 g/L)generated in the anodization treatment step at a liquid temperature of30° C., to the aluminum plate using a spray for 3 seconds.

(B-f) First Stage Anodization Treatment

A first stage anodization treatment was performed by an anodizationdevice having a structure illustrated in FIG. 3 using DC electrolysis.The anodization treatment was performed using a 170 g/L sulfuric acidaqueous solution as an electrolytic solution under conditions of aliquid temperature of 50° C. and a current density of 30 A/dm² to forman anodized film having a coating amount of 0.3 g/m².

(B-g) Pore Widening Treatment

The aluminum plate after being subjected to the anodization treatmentwas subjected to a pore widening treatment by being immersed in acaustic soda aqueous solution having a caustic soda concentration of 5%by mass and an aluminum ion concentration of 0.5% by mass at atemperature of 40° C. for 3 seconds.

(B-h) Second Stage Anodization Treatment

A second stage anodization treatment was performed by an anodizationdevice having a structure illustrated in FIG. 3 using DC electrolysis.The anodization treatment was performed using a 170 g/L sulfuric acidaqueous solution as an electrolytic solution under conditions of aliquid temperature of 50° C. and a current density of 13 A/dm² to forman anodized film having a coating amount of 2.1 g/m². The averagediameter of the micropores was 30 nm.

<Preparation of Support 6>

The following treatments (D-a) to (D-l) were performed on an aluminumplate formed of a material 1S having a thickness of 0.3 mm, therebypreparing a support 6. Moreover, during all treatment steps, a waterwashing treatment was performed, and liquid cutting was performed usinga nip roller after the water washing treatment.

(D-a) Mechanical Roughening Treatment (Brush Grain Method)

While supplying a suspension of pumice (specific gravity of 1.1 g/cm³)to the surface of the aluminum plate as a polishing slurry liquid usinga device illustrated in FIG. 5 , a mechanical roughening treatment wasperformed using rotating bundle bristle brushes. In FIG. 5 , thereference numeral 1 represents an aluminum plate, the reference numerals2 and 4 represent roller-like brushes (in the present examples, bundlebristle brushes), the reference numeral 3 represents a polishing slurryliquid, and the reference numerals 5, 6, 7, and 8 represent a supportroller.

The mechanical roughening treatment was performed under conditions inwhich the median diameter (m) of a polishing material was 30 mm, thenumber of the brushes was four, and the rotation speed (rpm) of thebrushes was set to 250 rpm. The material of the bundle bristle brusheswas nylon 6.10, the diameter of the brush bristles was 0.3 mm, and thebristle length was 50 mm. The brushes were produced by implantingbristles densely into the holes in a stainless steel cylinder having adiameter of 300 mm. The distance between two support rollers (a diameterof 200 mm) of the lower portion of the bundle bristle brush was 300 mm.The bundle bristle brushes were pressed until the load of a drivingmotor for rotating the brushes became 10 kW plus with respect to theload before the bundle bristle brushes were pressed against the aluminumplate. The rotation direction of the brushes was the same as the movingdirection of the aluminum plate.

(D-b) Alkali Etching Treatment

The aluminum plate was subjected to an etching treatment by spraying acaustic soda aqueous solution having a caustic soda concentration of 26%by mass and an aluminum ion concentration of 6.5% by mass, to thealuminum plate using a spray at a temperature of 70° C. The amount ofaluminum dissolved in the surface to be subsequently subjected to anelectrochemical roughening treatment was 10 g/m².

(D-c) Desmutting Treatment Using Acidic Aqueous Solution

A desmutting treatment was performed by spraying, as an acidic aqueoussolution, a waste liquid of nitric acid used for the electrochemicalroughening treatment in the subsequent step at a liquid temperature of35° C., to the aluminum plate using a spray for 3 seconds.

(D-d) Electrochemical Roughening Treatment Using Nitric Acid AqueousSolution

An electrochemical roughening treatment was continuously performed usingan AC voltage of 60 Hz. As an electrolytic solution, an electrolyticsolution which had been adjusted to have an aluminum ion concentrationof 4.5 g/L by adding aluminum nitrate to an aqueous solution having anitric acid concentration of 10.4 g/L at a liquid temperature of 35° C.was used. The AC power source waveform is a waveform illustrated in FIG.1 . Further, using a trapezoidal rectangular waveform AC having a timetp, until the current value reached a peak from zero, of 0.8 msec and aduty ratio of 1:1 as the AC power source waveform, the electrochemicalroughening treatment was performed using a carbon electrode as a counterelectrode. As an auxiliary anode, ferrite was used. An electrolytic cellillustrated in FIG. 2 was used as the electrolytic cell. The currentdensity was 30 A/dm² in terms of the peak current value, and 5% of thecurrent from the power source was separately flowed to the auxiliaryanode. The electric quantity (C/dm²) was 185 C/dm² as the total electricquantity during the anodization of the aluminum plate.

(D-e) Alkali Etching Treatment

An aluminum plate was subjected to an etching treatment by spraying acaustic soda aqueous solution having a caustic soda concentration of 27%by mass and an aluminum ion concentration of 2.5% by mass, to thealuminum plate using a spray at a temperature of 50° C. The amount ofaluminum dissolved was 3.5 g/m².

(D-f) Desmutting Treatment Using Acidic Aqueous Solution

A desmutting treatment was performed by spraying, as an acidic aqueoussolution, an aqueous solution having a sulfuric acid concentration of170 g/L and an aluminum ion concentration of 5 g/L at a liquidtemperature of 30° C., to the aluminum plate using a spray for 3seconds.

(D-g) Electrochemical Roughening Treatment Using Hydrochloric AcidAqueous Solution

An electrochemical roughening treatment was continuously performed usingan AC voltage of 60 Hz. As an electrolytic solution, an electrolyticsolution which had been adjusted to have an aluminum ion concentrationof 4.5 g/L by adding aluminum chloride to an aqueous solution having 6.2g/L of hydrochloric acid at a liquid temperature of 35° C. was used. TheAC power source waveform is a waveform illustrated in FIG. 1 . Further,using a trapezoidal rectangular waveform AC having a time tp, until thecurrent value reached a peak from zero, of 0.8 msec and a duty ratio of1:1 as the AC power source waveform, the electrochemical rougheningtreatment was performed using a carbon electrode as a counter electrode.As an auxiliary anode, ferrite was used. An electrolytic cellillustrated in FIG. 2 was used as the electrolytic cell. The currentdensity was 25 A/dm² in terms of the peak current value, and theelectric quantity (C/dm²) in the hydrochloric acid electrolysis was 63C/dm² as the total electric quantity during the anodization of thealuminum plate.

(D-h) Alkali Etching Treatment

An aluminum plate was subjected to an etching treatment by spraying acaustic soda aqueous solution having a caustic soda concentration of 5%by mass and an aluminum ion concentration of 0.5% by mass, to thealuminum plate using a spray at a temperature of 60° C. The amount ofaluminum dissolved was 0.2 g/m².

(D-i) Desmutting Treatment Using Acidic Aqueous Solution

A desmutting treatment was performed by spraying, as an acidic aqueoussolution, a waste liquid (an aqueous solution having a sulfuric acidconcentration of 170 g/L and an aluminum ion concentration of 5 g/L)generated in the anodization treatment step at a liquid temperature of35° C., to the aluminum plate using a spray for 4 seconds.

(D-j) Anodization Treatment

An anodization treatment was performed by an anodization device having astructure illustrated in FIG. 3 using DC electrolysis. The anodizationtreatment was performed using a 170 g/L sulfuric acid aqueous solutionas an electrolytic solution under conditions of a liquid temperature of50° C. and a current density of 30 A/dm² to form an anodized film havinga coating amount of 2.4 g/m².

(D-k) Pore Widening Treatment

The aluminum plate after being subjected to the anodization treatmentwas subjected to a pore widening treatment by being immersed in acaustic soda aqueous solution having a caustic soda concentration of 5%by mass and an aluminum ion concentration of 0.5% by mass at atemperature of 40° C. for 3 seconds. The average diameter of themicropores was 30 nm.

(D-l) Hydrophilization Treatment

In order to ensure the hydrophilicity of a non-image area, the aluminumplate was subjected to a silicate treatment by being immersed using 2.5%by mass of a No. 3 sodium silicate aqueous solution at 50° C. for 7seconds. The adhesion amount of Si was 8.5 mg/m².

<Preparation of Support 7>

The following treatments (F-a) to (F-g) were performed on an aluminumplate formed of a material 1S having a thickness of 0.3 mm, therebypreparing a support 7. Moreover, during all treatment steps, a waterwashing treatment was performed, and liquid cutting was performed usinga nip roller after the water washing treatment.

(F-a) Alkali Etching Treatment

The aluminum plate was subjected to an etching treatment by spraying acaustic soda aqueous solution having a caustic soda concentration of 26%by mass and an aluminum ion concentration of 6.5% by mass, to thealuminum plate using a spray at a temperature of 70° C. The amount ofaluminum dissolved in the surface to be subsequently subjected to anelectrochemical roughening treatment was 5 g/m².

(F-b) Desmutting Treatment Using Acidic Aqueous Solution

A desmutting treatment was performed by spraying, as an acidic aqueoussolution, an aqueous solution having a sulfuric acid concentration of150 g/L at a liquid temperature of 30° C., to the aluminum plate using aspray for 3 seconds.

(F-c) Electrochemical Roughening Treatment

An electrochemical roughening treatment was performed using the ACcurrent and an electrolytic solution having a hydrochloric acidconcentration of 14 g/L, an aluminum ion concentration of 13 g/L, and asulfuric acid concentration of 3 g/L. The liquid temperature of theelectrolytic solution was 30° C. The aluminum ion concentration wasadjusted by adding aluminum chloride.

The waveform of the AC current was a sine wave in which the positive andnegative waveforms were symmetrical, the frequency was 50 Hz, the ratiobetween the anodic reaction time and the cathodic reaction time in onecycle of the AC current was 1:1, and the current density was 75 A/dm² interms of the peak current value of the AC current waveform. Further, thetotal electric quantity of the aluminum plate used for the anodicreaction was 450 C/dm², and the electrolytic treatment was performedfour times at energization intervals of 4 seconds for each of theelectric quantity of 112.5 C/dm². A carbon electrode was used as acounter electrode of the aluminum plate.

(F-d) Alkali Etching Treatment

The aluminum plate was subjected to an etching treatment by spraying acaustic soda aqueous solution having a caustic soda concentration of 5%by mass and an aluminum ion concentration of 0.5% by mass, to thealuminum plate using a spray at a temperature of 45° C. The amount ofaluminum dissolved in the surface after being subjected to anelectrochemical roughening treatment was 0.2 g/m².

(F-e) Desmutting Treatment Using Acidic Aqueous Solution

A desmutting treatment was performed by spraying, as an acidic aqueoussolution, an aqueous solution having a sulfuric acid concentration of170 g/L and an aluminum ion concentration of 5 g/L at a liquidtemperature of 35° C., to the aluminum plate using a spray for 3seconds.

(F-f) First Stage Anodization Treatment

A first stage anodization treatment was performed by an anodizationdevice having a structure illustrated in FIG. 3 using DC electrolysis.The anodization treatment was performed using a 150 g/L phosphoric acidaqueous solution as an electrolytic solution under conditions of aliquid temperature of 35° C. and a current density of 4.5 A/dm² to forman anodized film having a coating amount of 1 g/m².

(F-g) Second Stage Anodization Treatment

A second stage anodization treatment was performed by an anodizationdevice having a structure illustrated in FIG. 3 using DC electrolysis.The anodization treatment was performed using a 170 g/L sulfuric acidaqueous solution as an electrolytic solution under conditions of aliquid temperature of 50° C. and a current density of 13 A/dm² to forman anodized film having a coating amount of 2.1 g/m². The averagediameter of the micropores was 40 nm.

<Preparation of Support 8>

The following treatments (G-a) to (G-h) were performed on an aluminumplate formed of a material 1S having a thickness of 0.3 mm, therebypreparing a support 8. Moreover, during all treatment steps, a waterwashing treatment was performed, and liquid cutting was performed usinga nip roller after the water washing treatment.

(G-a) Alkali Etching Treatment

The aluminum plate was subjected to an etching treatment by spraying acaustic soda aqueous solution having a caustic soda concentration of 26%by mass and an aluminum ion concentration of 6.5% by mass, to thealuminum plate using a spray at a temperature of 70° C. The amount ofaluminum dissolved in the surface to be subsequently subjected to anelectrochemical roughening treatment was 5 g/m².

(G-b) Desmutting Treatment Using Acidic Aqueous Solution

A desmutting treatment was performed by spraying, as an acidic aqueoussolution, an aqueous solution having a sulfuric acid concentration of150 g/L at a liquid temperature of 30° C., to the aluminum plate using aspray for 3 seconds.

(G-c) Electrochemical Roughening Treatment

An electrochemical roughening treatment was performed using the ACcurrent and an electrolytic solution having a hydrochloric acidconcentration of 14 g/L, an aluminum ion concentration of 13 g/L, and asulfuric acid concentration of 3 g/L. The liquid temperature of theelectrolytic solution was 30° C. The aluminum ion concentration wasadjusted by adding aluminum chloride.

The waveform of the AC current was a sine wave in which the positive andnegative waveforms were symmetrical, the frequency was 50 Hz, the ratiobetween the anodic reaction time and the cathodic reaction time in onecycle of the AC current was 1:1, and the current density was 75 A/dm² interms of the peak current value of the AC current waveform. Further, thetotal electric quantity of the aluminum plate used for the anodicreaction was 450 C/dm², and the electrolytic treatment was performedfour times at energization intervals of 4 seconds for each of theelectric quantity of 112.5 C/dm². A carbon electrode was used as acounter electrode of the aluminum plate.

(G-d) Alkali Etching Treatment

The aluminum plate was subjected to an etching treatment by spraying acaustic soda aqueous solution having a caustic soda concentration of 5%by mass and an aluminum ion concentration of 0.5% by mass, to thealuminum plate using a spray at a temperature of 45° C. The amount ofaluminum dissolved in the surface after being subjected to anelectrochemical roughening treatment was 0.2 g/m².

(G-e) Desmutting Treatment Using Acidic Aqueous Solution

A desmutting treatment was performed by spraying, as an acidic aqueoussolution, an aqueous solution having a sulfuric acid concentration of170 g/L and an aluminum ion concentration of 5 g/L at a liquidtemperature of 35° C., to the aluminum plate using a spray for 3seconds.

(G-f) First Stage Anodization Treatment

A first stage anodization treatment was performed by an anodizationdevice having a structure illustrated in FIG. 3 using DC electrolysis.The anodization treatment was performed using a 150 g/L phosphoric acidaqueous solution as an electrolytic solution under conditions of aliquid temperature of 35° C. and a current density of 4.5 A/dm² to forman anodized film having a coating amount of 1 g/m².

(G-g) Pore Widening Treatment

The aluminum plate after being subjected to the anodization treatmentwas subjected to a pore widening treatment by being immersed in acaustic soda aqueous solution having a caustic soda concentration of 5%by mass and an aluminum ion concentration of 0.5% by mass at atemperature of 40° C. for 4 seconds.

(G-h) Second Stage Anodization Treatment

A second stage anodization treatment was performed by an anodizationdevice having a structure illustrated in FIG. 3 using DC electrolysis.The anodization treatment was performed using a 170 g/L sulfuric acidaqueous solution as an electrolytic solution under conditions of aliquid temperature of 50° C. and a current density of 13 A/dm² to forman anodized film having a coating amount of 2.1 g/m². The averagediameter of the micropores was 100 nm.

<Preparation of Support 9>

A support 9 was prepared in the same manner as in the preparation of thesupport 7 except that the second stage anodization treatment (F-g) waschanged as follows in the preparation of the support 7.

(H-g) Second Stage Anodization Treatment

The anodization treatment was performed using a 150 g/L phosphoric acidaqueous solution as an electrolytic solution under conditions of aliquid temperature of 35° C. and a current density of 4.5 A/dm² to forman anodized film having a coating amount of 1.2 g/m². The averagediameter of the micropores was 40 nm.

<Preparation of Support 10>

A support 10 was prepared in the same manner as in the preparation ofthe support 8 except that the immersion time in the pore wideningtreatment (G-g) was changed to 8 seconds and the second stageanodization treatment (G-h) was changed as follows in the preparation ofthe support 8.

(I-h) Second Stage Anodization Treatment

The anodization treatment was performed using a 150 g/L phosphoric acidaqueous solution as an electrolytic solution under conditions of aliquid temperature of 35° C. and a current density of 4.5 A/dm² to forman anodized film having a coating amount of 2.1 g/m². The averagediameter of the micropores was 148 nm.

<Preparation of Support 11>

A molten metal was prepared using an aluminum alloy containing 0.06% bymass of Si, 0.30% by mass of Fe, 0.005% by mass of Cu, 0.001% by mass ofMn, 0.001% by mass of Mg, 0.001% by mass of Zn, and 0.03% by mass of Tiand, as the remainder, aluminum and unavoidable impurities, a moltenmetal treatment and filtration were performed, and an ingot having athickness of 500 mm and a width of 1200 mm was prepared according to aDC casting method. The surface was scraped off using a surface grinderhaving an average thickness of 10 mm and heated at 550° C. andmaintained the state for approximately 5 hours. After the temperaturewas decreased to 400° C., a rolled sheet having a thickness of 2.7 mmwas obtained using a hot rolling mill. Further, a heat treatment wasperformed thereon at 500° C. using a continuous annealing machine, and acold rolling was performed so that the thickness of the rolled sheet wasfinished to 0.24 mm, thereby preparing an aluminum plate (width of 1030mm) formed of JIS 1050 material.

The following surface treatments (b) to (j) were continuously performedon an aluminum plate, thereby preparing a support 11. Moreover, duringall treatment steps, a water washing treatment was performed, and liquidcutting was performed using a nip roller after the water washingtreatment.

(b) Alkali Etching Treatment

The aluminum plate was subjected to an etching treatment by spraying anaqueous solution having a caustic soda concentration of 2.6% by mass andan aluminum ion concentration of 6.5% by mass at a temperature of 70° C.so that 6 g/m² of the aluminum plate was dissolved.

(c) Desmutting Treatment

A desmutting treatment was performed by spraying an acidic aqueoussolution (containing 0.5% by mass of aluminum ions) having a nitric acidconcentration of 1% by mass at a temperature of 30° C. using a spray. Asthe nitric acid aqueous solution used for the desmutting treatment, awaste liquid used for the step of performing the electrochemicalroughening treatment using the alternating current in a nitric acidaqueous solution was used.

(d) Electrochemical Roughening Treatment

An electrochemical roughening treatment was continuously performed usingan AC voltage of 60 Hz. As an electrolytic solution, an aqueous solutioncontaining 10.5 g/L of nitric acid (containing 5 g/L of aluminum ionsand 0.007% by mass of ammonium ions) at a liquid temperature of 50° C.was used. The AC power source waveform is a waveform illustrated in FIG.1 . Further, using a trapezoidal rectangular waveform AC having a timetp, until the current value reached a peak from zero, of 0.8 msec and aduty ratio of 1:1 as the AC power source waveform, the electrochemicalroughening treatment was performed using a carbon electrode as a counterelectrode. As an auxiliary anode, ferrite was used. An electrolytic cellillustrated in FIG. 2 was used as the electrolytic cell. The currentdensity was 30 A/dm² in terms of the peak current value, and theelectric quantity was 220 C/dm² as the total electric quantity duringthe anodization of the aluminum plate. Further, 5% of the current fromthe power source was separately flowed to the auxiliary anode.

(e) Alkali Etching Treatment

The aluminum plate was subjected to an etching treatment by spraying anaqueous solution having a caustic soda concentration of 26% by mass andan aluminum ion concentration of 6.5% by mass at a temperature of 32° C.so that 0.25 g/m² of the aluminum plate was dissolved. Further, a smutcomponent mainly containing aluminum hydroxide generated during theelectrochemical roughening treatment using the alternating current atthe former stage was removed, an edge portion of a generated pit wasdissolved to smooth the edge portion.

(f) Desmutting Treatment

A desmutting treatment was performed by spraying an aqueous solution(containing 4.5% by mass of aluminum ions) having a sulfuric acidconcentration of 15% by mass at a temperature of 30° C. using a spray.As the nitric acid aqueous solution used for the desmutting treatment, awaste liquid used for the step of performing the electrochemicalroughening treatment using the alternating current in a nitric acidaqueous solution was used.

(g) Electrochemical Roughening Treatment

An electrochemical roughening treatment was continuously performed usingan AC voltage of 60 Hz. As an electrolytic solution, an aqueous solutioncontaining 2.5 g/L of hydrochloric acid (containing 5 g/L of aluminumions) at a temperature of 35° C. was used. The AC power source waveformis a waveform illustrated in FIG. 1 . Further, using a trapezoidalrectangular waveform AC having a time tp, until the current valuereached a peak from zero, of 0.8 msec and a duty ratio of 1:1 as the ACpower source waveform, the electrochemical roughening treatment wasperformed using a carbon electrode as a counter electrode. As anauxiliary anode, ferrite was used. An electrolytic cell illustrated inFIG. 2 was used as the electrolytic cell. The current density was 25A/dm² in terms of the peak current value, and the electric quantity was50 C/dm² as the total electric quantity during the anodization of thealuminum plate.

(h) Alkali Etching Treatment

The aluminum plate was subjected to an etching treatment by spraying anaqueous solution having a caustic soda concentration of 26% by mass andan aluminum ion concentration of 6.5% by mass at a temperature of 32° C.so that 0.1 g/m² of the aluminum plate was dissolved. Further, a smutcomponent mainly containing aluminum hydroxide generated during theelectrochemical roughening treatment using the alternating current atthe former stage was removed, an edge portion of a generated pit wasdissolved to smooth the edge portion.

(i) Desmutting Treatment

A desmutting treatment was performed by spraying an aqueous solution(containing 0.5% by mass of aluminum ions) having a sulfuric acidconcentration of 25% by mass at a temperature of 60° C. using a spray.

(j) Anodization Treatment

An anodization treatment was performed by an anodization device having astructure illustrated in FIG. 3 using DC electrolysis. The anodizationtreatment was performed using an aqueous solution (containing 0.5% bymass of aluminum ions) having a sulfuric acid concentration of 170 g/Las an electrolytic solution under conditions of a liquid temperature of38° C. and a current density of 30 A/dm² to form an anodized film havinga coating amount of 2.7 g/m². The average diameter of the micropores was7 nm.

<Preparation of Support 12>

In order to remove rolling oil on a surface of an aluminum plate(material JIS A 1050) having a thickness of 0.3 mm, after a degreasingtreatment was performed at 50° C. for 30 seconds using a 10 mass %sodium aluminate aqueous solution, the surface of the aluminum plate wasgrained using three bundle nylon brushes having a hair diameter of 0.3mm and a pumice-water suspension (specific gravity of 1.1 g/cm³) havinga median diameter of 25 μm, and the surface was thoroughly washed withwater. The aluminum plate was etched by being immersed in a 25 mass %sodium hydroxide aqueous solution at 45° C. for 9 seconds, washed withwater, further immersed in a 20 mass % nitric acid aqueous solution at60° C. for 20 seconds, and washed with water. The etching amount of thegrained surface was approximately 3 g/m².

An electrochemical roughening treatment was continuously performed usingan AC voltage of 60 Hz. An aqueous solution (containing 0.5% by mass ofaluminum ions) having a nitric acid concentration of 1% by mass was usedas the electrolytic solution, and the liquid temperature was 50° C.Using a trapezoidal rectangular waveform AC having a time tp, until thecurrent value reached a peak from zero, of 0.8 msec and a duty ratio of1:1 as the AC power source waveform, the electrochemical rougheningtreatment was performed using a carbon electrode as a counter electrode.As an auxiliary anode, ferrite was used. The current density was 30A/dm² in terms of the peak current value, and 5% of the current from thepower source was separately flowed to the auxiliary anode. The electricquantity in the nitric acid electrolysis was 175 C/dm² as the electricquantity during the anodization of the aluminum plate. Thereafter, thealuminum plate was washed with water using a spray.

Next, the aluminum plate was subjected to an electrochemical rougheningtreatment according to the same method as that for the nitric acidelectrolysis under conditions of an electric quantity of 50 C/dm² duringthe anodization using an aqueous solution (containing 0.5% by mass ofaluminum ions) containing 0.5% by mass of hydrochloric acid and anelectrolytic solution at a liquid temperature of 50° C., and thealuminum plate was washed with water using a spray.

A DC anodized film having a coating amount of 2.5 g/m² at a currentdensity of 15 A/dm² was provided on the aluminum plate using a 15 mass %sulfuric acid aqueous solution (containing 0.5% by mass of aluminumions) as an electrolytic solution, washed with water, and dried.

Next, a sealing treatment was performed by spraying water vapor at 100°C. to the anodized film at a pressure of 1.033×10⁵ Pa for 8 seconds.Further, the aluminum support was immersed in a treatment liquidobtained by dissolving 0.4% by mass of polyvinyl phosphonic acid(manufactured by PCAS) in pure water at 53° C. for 10 seconds, and theexcess treatment liquid was completely removed by a nip roll, therebypreparing a support 12.

<Preparation of Support 13>

An aluminum plate formed of a material 1S having a thickness of 0.19 mmwas immersed in a 40 g/L sodium hydroxide aqueous solution at 60° C. for8 seconds so as to be degreased and then washed with demineralized waterfor 2 seconds. The aluminum plate was subjected to an electrochemicalroughening treatment in an aqueous solution containing 12 g/L ofhydrochloric acid and 38 g/L of aluminum sulfate (18 hydrate) at atemperature of 33° C. and at a current density of 130 A/dm² using an ACfor 15 seconds. Next, the aluminum plate was washed with demineralizedwater for 2 seconds, subjected to a desmutting treatment by being etchedusing 155 g/L of a sulfuric acid aqueous solution at 70° C. for 4seconds, and washed with demineralized water at 25° C. for 2 seconds.The aluminum plate was subjected to an anodization treatment in 155 g/Lof a sulfuric acid aqueous solution for 13 seconds at a temperature of45° C. and at a current density of 22 A/dm² and washed withdemineralized water for 2 seconds. Further, the aluminum plate wastreated at 40° C. for 10 seconds using 4 g/L of a polyvinyl phosphonicacid aqueous solution, washed with demineralized water at 20° C. for 2seconds, and then dried, thereby preparing a support 13. The averagediameter of the micropores was 7 nm.

<Preparation of Support 14>

The following treatments (K-a) to (K-l) were performed on an aluminumplate formed of a material 1S having a thickness of 0.3 mm, therebypreparing a support 14. Moreover, during all treatment steps, a waterwashing treatment was performed, and liquid cutting was performed usinga nip roller after the water washing treatment.

(D-a) Mechanical Roughening Treatment (Brush Grain Method)

While supplying a suspension of pumice (specific gravity of 1.1 g/cm³)to the surface of the aluminum plate as a polishing slurry liquid usinga device illustrated in FIG. 5 , a mechanical roughening treatment wasperformed using rotating bundle bristle brushes. The mechanicalroughening treatment was performed under conditions in which the mediandiameter (μm) of a polishing material was 30 mm, the number of thebrushes was four, and the rotation speed (rpm) of the brushes was set to250 rpm. The material of the bundle bristle brushes was nylon 6.10, thediameter of the brush bristles was 0.3 mm, and the bristle length was 50mm. The brushes were produced by implanting bristles densely into theholes in a stainless steel cylinder having a diameter of 300 mm. Thedistance between two support rollers (a diameter of 200 mm) of the lowerportion of the bundle bristle brush was 300 mm. The bundle bristlebrushes were pressed until the load of a driving motor for rotating thebrushes became 10 kW plus with respect to the load before the bundlebristle brushes were pressed against the aluminum plate. The rotationdirection of the brushes was the same as the moving direction of thealuminum plate.

(K-b) Alkali Etching Treatment

The aluminum plate was subjected to an etching treatment by spraying acaustic soda aqueous solution having a caustic soda concentration of 26%by mass and an aluminum ion concentration of 6.5% by mass, to thealuminum plate using a spray at a temperature of 70° C. The amount ofaluminum dissolved in the surface to be subsequently subjected to anelectrochemical roughening treatment was 10 g/m².

(K-c) Desmutting Treatment Using Acidic Aqueous Solution

A desmutting treatment was performed by spraying, as an acidic aqueoussolution, a waste liquid of nitric acid used for the electrochemicalroughening treatment in the subsequent step at a liquid temperature of35° C., to the aluminum plate using a spray for 3 seconds.

(K-d) Electrochemical Roughening Treatment Using Nitric Acid AqueousSolution

An electrochemical roughening treatment was continuously performed usingan AC voltage of 60 Hz. As an electrolytic solution, an electrolyticsolution which had been adjusted to have an aluminum ion concentrationof 4.5 g/L by adding aluminum nitrate to an aqueous solution having anitric acid concentration of 10.4 g/L at a liquid temperature of 35° C.was used. The AC power source waveform is a waveform illustrated in FIG.1 . Further, using a trapezoidal rectangular waveform AC having a timetp, until the current value reached a peak from zero, of 0.8 msec and aduty ratio of 1:1 as the AC power source waveform, the electrochemicalroughening treatment was performed using a carbon electrode as a counterelectrode. As an auxiliary anode, ferrite was used. An electrolytic cellillustrated in FIG. 2 was used as the electrolytic cell. The currentdensity was 30 A/dm² in terms of the peak current value, and 5% of thecurrent from the power source was separately flowed to the auxiliaryanode. The electric quantity (C/dm²) was 185 C/dm² as the total electricquantity during the anodization of the aluminum plate.

(K-e) Alkali Etching Treatment

An aluminum plate was subjected to an etching treatment by spraying acaustic soda aqueous solution having a caustic soda concentration of 27%by mass and an aluminum ion concentration of 2.5% by mass, to thealuminum plate using a spray at a temperature of 50° C. The amount ofaluminum dissolved was 0.5 g/m².

(K-f) Desmutting Treatment Using Acidic Aqueous Solution

A desmutting treatment was performed by spraying, as an acidic aqueoussolution, an aqueous solution having a sulfuric acid concentration of170 g/L and an aluminum ion concentration of 5 g/L at a liquidtemperature of 30° C., to the aluminum plate using a spray for 3seconds.

(K-g) Electrochemical Roughening Treatment Using Hydrochloric AcidAqueous Solution

An electrochemical roughening treatment was continuously performed usingan AC voltage of 60 Hz. As an electrolytic solution, an electrolyticsolution which had been adjusted to have an aluminum ion concentrationof 4.5 g/L by adding aluminum chloride to an aqueous solution having 6.2g/L of hydrochloric acid at a liquid temperature of 35° C. was used. TheAC power source waveform is a waveform illustrated in FIG. 1 . Further,using a trapezoidal rectangular waveform AC having a time tp, until thecurrent value reached a peak from zero, of 0.8 msec and a duty ratio of1:1 as the AC power source waveform, the electrochemical rougheningtreatment was performed using a carbon electrode as a counter electrode.As an auxiliary anode, ferrite was used. An electrolytic cellillustrated in FIG. 2 was used as the electrolytic cell. The currentdensity was 25 A/dm² in terms of the peak current value, and theelectric quantity (C/dm²) in the hydrochloric acid electrolysis was 63C/dm² as the total electric quantity during the anodization of thealuminum plate.

(K-h) Alkali Etching Treatment

An aluminum plate was subjected to an etching treatment by spraying acaustic soda aqueous solution having a caustic soda concentration of 5%by mass and an aluminum ion concentration of 0.5% by mass, to thealuminum plate using a spray at a temperature of 60° C. The amount ofaluminum dissolved was 0.1 g/m².

(K-i) Desmutting Treatment Using Acidic Aqueous Solution

A desmutting treatment was performed by spraying, as an acidic aqueoussolution, a waste liquid (an aqueous solution having a sulfuric acidconcentration of 170 g/L and an aluminum ion concentration of 5 g/L)generated in the anodization treatment step at a liquid temperature of35° C., to the aluminum plate using a spray for 4 seconds.

(K-j) Anodization Treatment

An anodization treatment was performed by an anodization device having astructure illustrated in FIG. 3 using DC electrolysis. The anodizationtreatment was performed using a 170 g/L sulfuric acid aqueous solutionas an electrolytic solution under conditions of a liquid temperature of50° C. and a current density of 30 A/dm² to form an anodized film havinga coating amount of 2.4 g/m².

(K-k) Hydrophilization Treatment

In order to ensure the hydrophilicity of a non-image area, the aluminumplate was subjected to a silicate treatment by being immersed using 2.5%by mass of a No. 3 sodium silicate aqueous solution at 50° C. for 7seconds. The adhesion amount of Si was 8.5 mg/m².

<Preparation of Support 15>

The following treatments (J-a) to (J-m) were performed on an aluminumplate formed of a material 1S having a thickness of 0.3 mm, therebypreparing a support 15. Moreover, during all treatment steps, a waterwashing treatment was performed, and liquid cutting was performed usinga nip roller after the water washing treatment.

(J-a) Mechanical Roughening Treatment (Brush Grain Method)

While supplying a suspension of pumice (specific gravity of 1.1 g/cm³)to the surface of the aluminum plate as a polishing slurry liquid usinga device illustrated in FIG. 5 , a mechanical roughening treatment wasperformed using rotating bundle bristle brushes. The mechanicalroughening treatment was performed under conditions in which the mediandiameter (m) of a polishing material was 30 mm, the number of thebrushes was four, and the rotation speed (rpm) of the brushes was set to250 rpm. The material of the bundle bristle brushes was nylon 6.10, thediameter of the brush bristles was 0.3 mm, and the bristle length was 50mm. The brushes were produced by implanting bristles densely into theholes in a stainless steel cylinder having a diameter of 300 mm. Thedistance between two support rollers (a diameter of 200 mm) of the lowerportion of the bundle bristle brush was 300 mm. The bundle bristlebrushes were pressed until the load of a driving motor for rotating thebrushes became 10 kW plus with respect to the load before the bundlebristle brushes were pressed against the aluminum plate. The rotationdirection of the brushes was the same as the moving direction of thealuminum plate.

(J-b) Alkali Etching Treatment

The aluminum plate was subjected to an etching treatment by spraying acaustic soda aqueous solution having a caustic soda concentration of 26%by mass and an aluminum ion concentration of 6.5% by mass, to thealuminum plate using a spray at a temperature of 70° C. The amount ofaluminum dissolved in the surface to be subsequently subjected to anelectrochemical roughening treatment was 10 g/m².

(J-c) Desmutting Treatment Using Acidic Aqueous Solution

A desmutting treatment was performed by spraying, as an acidic aqueoussolution, a waste liquid of nitric acid used for the electrochemicalroughening treatment in the subsequent step at a liquid temperature of35° C., to the aluminum plate using a spray for 3 seconds.

(J-d) Electrochemical Roughening Treatment Using Nitric Acid AqueousSolution

An electrochemical roughening treatment was continuously performed usingan AC voltage of 60 Hz. As an electrolytic solution, an electrolyticsolution which had been adjusted to have an aluminum ion concentrationof 4.5 g/L by adding aluminum nitrate to an aqueous solution having anitric acid concentration of 10.4 g/L at a liquid temperature of 35° C.was used. The AC power source waveform is a waveform illustrated in FIG.1 . Further, using a trapezoidal rectangular waveform AC having a timetp, until the current value reached a peak from zero, of 0.8 msec and aduty ratio of 1:1 as the AC power source waveform, the electrochemicalroughening treatment was performed using a carbon electrode as a counterelectrode. As an auxiliary anode, ferrite was used. An electrolytic cellillustrated in FIG. 2 was used as the electrolytic cell. The currentdensity was 30 A/dm² in terms of the peak current value, and 5% of thecurrent from the power source was separately flowed to the auxiliaryanode. The electric quantity (C/dm²) was 185 C/dm² as the total electricquantity during the anodization of the aluminum plate.

(J-e) Alkali Etching Treatment

An aluminum plate was subjected to an etching treatment by spraying acaustic soda aqueous solution having a caustic soda concentration of 27%by mass and an aluminum ion concentration of 2.5% by mass, to thealuminum plate using a spray at a temperature of 50° C. The amount ofaluminum dissolved was 3.5 g/m².

(J-f) Desmutting Treatment Using Acidic Aqueous Solution

A desmutting treatment was performed by spraying, as an acidic aqueoussolution, an aqueous solution having a sulfuric acid concentration of170 g/L and an aluminum ion concentration of 5 g/L at a liquidtemperature of 30° C., to the aluminum plate using a spray for 3seconds.

(J-g) Electrochemical Roughening Treatment Using Hydrochloric AcidAqueous Solution

An electrochemical roughening treatment was continuously performed usingan AC voltage of 60 Hz. As an electrolytic solution, an electrolyticsolution which had been adjusted to have an aluminum ion concentrationof 4.5 g/L by adding aluminum chloride to an aqueous solution having 6.2g/L of hydrochloric acid at a liquid temperature of 35° C. was used. TheAC power source waveform is a waveform illustrated in FIG. 1 . Further,using a trapezoidal rectangular waveform AC having a time tp, until thecurrent value reached a peak from zero, of 0.8 msec and a duty ratio of1:1 as the AC power source waveform, the electrochemical rougheningtreatment was performed using a carbon electrode as a counter electrode.As an auxiliary anode, ferrite was used. An electrolytic cellillustrated in FIG. 2 was used as the electrolytic cell. The currentdensity was 25 A/dm² in terms of the peak current value, and theelectric quantity (C/dm²) in the hydrochloric acid electrolysis was 63C/dm² as the total electric quantity during the anodization of thealuminum plate.

(J-h) Alkali Etching Treatment

An aluminum plate was subjected to an etching treatment by spraying acaustic soda aqueous solution having a caustic soda concentration of 5%by mass and an aluminum ion concentration of 0.5% by mass, to thealuminum plate using a spray at a temperature of 60° C. The amount ofaluminum dissolved was 0.2 g/m².

(J-i) Desmutting Treatment Using Acidic Aqueous Solution

A desmutting treatment was performed by spraying, as an acidic aqueoussolution, a waste liquid (an aqueous solution having a sulfuric acidconcentration of 170 g/L and an aluminum ion concentration of 5 g/L)generated in the anodization treatment step at a liquid temperature of35° C., to the aluminum plate using a spray for 4 seconds.

(J-j) First Stage Anodization Treatment

A first stage anodization treatment was performed by an anodizationdevice having a structure illustrated in FIG. 3 using DC electrolysis.The anodization treatment was performed using a 170 g/L sulfuric acidaqueous solution as an electrolytic solution under conditions of aliquid temperature of 50° C. and a current density of 30 A/dm² to forman anodized film having a coating amount of 0.3 g/m².

(J-k) Pore Widening Treatment

The aluminum plate after being subjected to the anodization treatmentwas subjected to a pore widening treatment by being immersed in acaustic soda aqueous solution having a caustic soda concentration of 5%by mass and an aluminum ion concentration of 0.5% by mass at atemperature of 40° C. for 3 seconds.

(J-l) Second Stage Anodization Treatment

A second stage anodization treatment was performed by an anodizationdevice having a structure illustrated in FIG. 3 using DC electrolysis.The anodization treatment was performed using a 170 g/L sulfuric acidaqueous solution as an electrolytic solution under conditions of aliquid temperature of 50° C. and a current density of 13 A/dm² to forman anodized film having a coating amount of 2.1 g/m²

(J-m) Hydrophilization Treatment

In order to ensure the hydrophilicity of a non-image area, the aluminumplate was subjected to a silicate treatment by being immersed using 2.5%by mass of a No. 3 sodium silicate aqueous solution at 50° C. for 7seconds. The adhesion amount of Si was 8.5 mg/m². The average diameterof the micropores was 30 nm.

<Formation of Undercoat Layer 1>

The support was coated with an undercoat layer coating solution (1)having the following composition such that the dry coating amount wasset to 20 mg/m², thereby forming an undercoat layer 1.

(Undercoat Layer Coating Solution (1))

-   -   Compound (UC-l) for undercoat layer (the following structure):        0.18 parts    -   Hydroxyethyliminodiacetic acid: 0.05 parts    -   Surfactant (EMALEX 710, manufactured by Nihon Emulsion Co.,        Ltd.): 0.03 parts    -   Water: 28.0 parts

<Formation of Undercoat Layer 2>

The support was coated with an undercoat layer coating solution (2)having the following composition such that the dry coating amount wasset to 20 mg/m², thereby forming an undercoat layer 2.

(Undercoat Layer Coating Solution (2))

-   -   Compound (2) for undercoat layer (the following structure): 0.18        parts    -   Tetrasodium ethylenediamine tetraacetate: 0.10 parts    -   Polyoxyethylene lauryl ether: 0.03 parts    -   Water: 61.39 parts

The numbers on the lower right side of the parentheses of eachconstitutional unit in the compound (2) for an undercoat layer indicatethe mass ratios and the numbers on the lower right side of theparentheses of each ethyleneoxy unit indicate repetition numbers.

<Formation of Undercoat Layer 3>

The support was coated with an undercoat layer coating solution (3)having the following composition using a wire bar and dried at 90° C.for 30 seconds such that the dry coating amount was set to 0.5 mg/m²,thereby forming an undercoat layer 3.

(Undercoat Layer Coating Solution (3))

-   -   Polymer compound A (the following structure) (mass average        molecular weight: 30000): 0.0049 g    -   Methanol: 55.19 g    -   1-Methoxy-2-propanol: 0.0154 g    -   Pure water: 6.1432 g

<Formation of Undercoat Layer 4>

The support was coated with an undercoat layer coating solution (4)having the following composition using a bar coater and dried at 80° C.for 15 seconds such that the dry coating amount was set to 18 mg/m²,thereby forming an undercoat layer 4.

<Undercoat Layer Coating Solution (4)>

-   -   Polymer U (the following structure): 0.3 parts by mass    -   Pure water: 60.0 parts by mass    -   Methanol: 939.7 parts by mass

<Formation of Undercoat Layer 5>

The surface of the support 15 on the printing surface side was coatedwith an undercoat layer coating solution (5) having the followingcomposition such that the dry coating amount was set to 10 mg/m²,thereby forming an undercoat layer 5.

<Undercoat Layer Coating Solution (5)>

-   -   Compound (2) for undercoat layer (described above): 0.13 parts        by mass    -   Hydroxyethyliminodiacetic acid: 0.05 parts by mass    -   Tetrasodium ethylenediamine tetraacetate: 0.05 parts by mass    -   Polyoxyethylene lauryl ether: 0.03 parts by mass    -   Water: 61.39 parts by mass

<Formation of Image Recording Layer 1>

The support was bar-coated with an image recording layer coatingsolution (1) having the following composition and dried in an oven at100° C. for 60 seconds, thereby forming an image recording layer 1having a thickness of 0.6 μm.

(Image Recording Layer Coating Solution (1))

-   -   Infrared absorbing agent 4 (the following structure): 0.030        parts    -   Polymerization initiator I (the following structure): 0.032        parts    -   Polymerizable compound (1) A-9300 (manufactured by Shin-Nakamura        Chemical Co., Ltd.) (the following structure): 0.05 parts    -   Polymerizable compound (2) A-DPH (manufactured by Shin-Nakamura        Chemical Co., Ltd.) (the following structure): 0.05 parts    -   Binder polymer 3 (described below): 0.825 parts    -   Surfactant BYK306 (manufactured by BYK Chemie GmbH): 0.008 parts    -   1-Methoxy-2-propanol: 8.609 parts    -   Methyl ethyl ketone: 1.091 parts

(Synthesis of Binder Polymer 3)

300 g of methyl ethyl ketone was poured into a three-neck flask andheated to 80° C. in a nitrogen stream. A mixed solution consisting of50.0 g of the following compound 1, 30.0 g of the following compound 2,20.0 g of the following compound 3, 0.7 g of azobisisobutyronitrile(AIBN), and 100 g of methyl ethyl ketone was added dropwise to thereaction container for 30 minutes. After the completion of the dropwiseaddition, the reaction was allowed to further continue for 7.5 hours.Thereafter, 0.3 g of AIBN was added thereto, and the reaction wasallowed to further continue for 12 hours. After the completion of thereaction, the reaction solution was cooled to room temperature, therebyobtaining a binder polymer 3. The mass average molecular weight of theobtained binder polymer 3 was 75000.

<Formation of Image Recording Layer 2>

The undercoat layer was bar-coated with an image recording layer coatingsolution

(2) having the following composition and dried in an oven at 100° C. for60 seconds, thereby forming an image recording layer 2 having athickness of 1 μm.

The image recording layer coating solution (2) was obtained by mixing aphotosensitive solution (1) and a microgel solution (1) described belowimmediately before the coating and then stirring the solution.

(Image Recording Layer Coating Solution (2))

(Photosensitive Solution (1))

-   -   Binder polymer (1) (the following structure, Mw: 55000 and n        (number of ethylene oxide (EO) repeating units): 2): 0.240 parts    -   Infrared absorbing agent (1) (the following structure): 0.020        parts    -   Borate compound (1) (Sodium tetraphenyl borate): 0.010 parts    -   Polymerization initiator (1) (the following structure): 0.162        parts    -   Polymerizable compound (tris(acryloyloxyethyl) isocyanurate, NK        ESTER A-9300, manufactured by Shin-Nakamura Chemical Co., Ltd.):        0.192 parts    -   Anionic surfactant 1 (the following structure): 0.050 parts    -   Fluorine-based surfactant (1) (the following structure): 0.008        parts    -   2-Butanone: 1.091 parts    -   1-Methoxy-2-propanol: 8.609 parts

(Microgel Solution (1))

-   -   Microgel (1): 2.640 parts    -   Distilled water: 2.425 parts

Polymer moiety described above

The numbers on the lower right side of the parentheses of eachconstitutional unit in the binder polymer (1) indicate the molar ratios.Me represents a methyl group.

The numbers on the lower right side of the parentheses of eachconstitutional unit in the fluorine-based surfactant (1) indicate themolar ratios and the numbers on the lower right side of the parenthesesof each ethyleneoxy unit or each propyleneoxy unit indicate repetitionnumbers.

(Preparation of Microgel (1))

A method of preparing a microgel (1) used for the microgel solution (1)will be described below.

<Preparation of Polyvalent Isocyanate Compound (1)>

0.043 parts of bismuth tris(2-ethylhexanoate) (NEOSTANN U-600(manufactured by NITTO KASEI CO., LTD.)) was added to an ethyl acetate(25.31 parts) suspension solution of 17.78 parts (80 molar equivalent)of isophorone diisocyanate and 7.35 parts (20 molar equivalent) of thefollowing polyhydric phenol compound (1), and the resulting solution wasstirred. The reaction temperature was set to 500 in a case of heatgeneration being subsided, and the solution was stirred for 3 hours,thereby obtaining an ethyl acetate (50% by mass) solution of apolyvalent isocyanate compound (1).

<Preparation of Microgel (1)>

The oil phase components and the water phase components were mixed witheach other and emulsified at 12000 rpm for 10 minutes using ahomogenizer. The obtained emulsion was stirred at 45° C. for 4 hours,5.20 parts of a 10 mass % aqueous solution of1,8-diazabicyclo[5.4.0]undeca-7-ene-octylate (U-CAT SA102, manufacturedby San-Apro Ltd.) was added thereto, and the solution was stirred atroom temperature for 30 minutes and allowed to stand at 45° C. for 24hours. The concentration of solid contents was adjusted to 20% by massusing distilled water, thereby obtaining an aqueous dispersion liquid ofthe microgel (1). The volume average particle diameter was measuredusing a dynamic light scattering type particle size distributionmeasuring device LB-500 (manufactured by Horiba Ltd.) according to alight scattering method, and the value was 0.28 μm.

(Oil Phase Components)

(Component 1) ethyl acetate: 12.0 parts

(Component 2) adduct (50 mass % ethyl acetate solution, manufactured byMitsui Chemicals, Inc.) obtained by adding trimethylolpropane (6 mol)and xylene diisocyanate (18 mol) and adding methyl one-terminalpolyoxyethylene (1 mol, repetition number of oxyethylene units: 90)thereto: 3.76 parts

(Component 3) polyvalent isocyanate compound (1) (as 50 mass % ethylacetate solution): 15.0 parts

(Component 4) 65 mass % solution of dipentaerythritol pentaacrylate(SR-399, manufactured by Sartomer Japan Inc.) in ethyl acetate: 11.54parts

(Component 5) 10% solution of sulfonate type surfactant (PIONINE A-41-C,manufactured by TAKEMOTO OIL & FAT Co., Ltd.) in ethyl acetate: 4.42parts

(Water Phase Components)

Distilled water: 46.87 parts

<Formation of Image Recording Layer 3>

The undercoat layer was bar-coated with an image recording layer coatingsolution (3) having the following composition and dried in an oven at100° C. for 60 seconds, thereby forming an image recording layer 3having a thickness of 1 μm.

The image recording layer coating solution (3) was obtained by mixing aphotosensitive solution (2) and a microgel solution (2) described belowimmediately before the coating and then stirring the solution.

<Photosensitive Solution (2)>

-   -   Binder polymer (2) (the following structure, Mw: 50000 and n        (number of ethylene oxide (EO) repeating units): 4): 0.480 parts    -   Infrared absorbing agent (1) (described above): 0.030 parts    -   Borate compound (Sodium tetraphenyl borate): 0.014 parts    -   Polymerization initiator (1) (described above): 0.234 parts    -   Polymerizable compound (tris(acryloyloxyethyl) isocyanurate, NK        ESTER A-9300, manufactured by Shin-Nakamura Chemical Co., Ltd.):        0.192 parts        -   Low-molecular-weight hydrophilic compound (1)            (tris(2-hydroxyethyl)isocyanurate): 0.052 parts    -   Anionic surfactant 1 (described above): 0.099 g    -   Oil sensitizer phosphonium compound (1) (the following        structure): 0.12 parts        -   Oil sensitizer ammonium group-containing polymer (the            following structure, reduced specific viscosity of 44 ml/g):            0.035 parts    -   Oil sensitizer benzyl dimethyl octyl ammonium PF₆ salt: 0.032        parts    -   Colorant ethyl violet (the following structure): 0.030 parts    -   Fluorine-based surfactant (1) (described above): 0.02 parts    -   2-Butanone: 1.091 parts    -   1-Methoxy-2-propanol: 8.609 parts

The numbers on the lower right side of the parentheses of eachconstitutional unit in the binder polymer (2) and the ammoniumgroup-containing polymer indicate the molar ratios. Me represents amethyl group.

<Microgel Solution (2)>

-   -   Microgel (2): 1.580 parts    -   Distilled water: 1.455 parts

(Preparation of Microgel (2))

A method of preparing a microgel (2) used in the microgel solution (2)will be described below.

10 parts of an adduct (TAKENATE D-110N, manufactured by Mitsui Chemicalspolyurethanes, Inc.) of trimethylolpropane and xylene diisocyanate, 5.54parts of dipentaerythritol pentaacrylate (SR399, manufactured bySartomer Japan Inc.), and 0.1 parts of PIONINE A-41C (manufactured byTAKEMOTO OIL & FAT Co., Ltd.), as oil phase components, were dissolvedin 17 parts of ethyl acetate. As a water phase component, 40 parts of a4 mass % aqueous solution of PVA-205 was prepared. The oil phasecomponents and the water phase components were mixed with each other andemulsified at 12000 rpm for 10 minutes using a homogenizer. 25 parts ofdistilled water was added to the obtained emulsion, and the resultantwas stirred at room temperature (25° C., the same applies hereinafter)for 30 minutes and stirred at 50° C. for 3 hours. The microgel solutionobtained in this manner was diluted with distilled water such that theconcentration of solid contents was set to 15% by mass, therebypreparing a microgel (2). The average particle diameter of the microgelmeasured by a light scattering method was 0.2 mm.

<Formation of Image Recording Layer 4>

The support was bar-coated with an image recording layer coatingsolution (4) having the following composition and dried in an oven at120° C. for 40 seconds, thereby forming an image recording layer 4having a thickness of 1 μm.

<Image Recording Layer Coating Solution (4)>

-   -   Binder polymer (4) (the following structure): 4.09 parts by mass    -   SR399: 2.66 parts by mass    -   NK-Ester A-DPH: 2.66 parts by mass    -   CD9053: 0.53 parts by mass    -   Bis-t-butylphenyliodonium tetraphenylborate: 0.96 parts by mass    -   Fluor N2900: 0.11 parts by mass    -   Pigment 1 (described below): 0.73 parts by mass    -   Infrared absorbing agent (4) (the following structure): 0.27        parts by mass    -   PHOSMER PE (manufactured by Uni-Chemical Co., Ltd.): 0.55 parts        by mass    -   Ion exchange water: 13.77 parts    -   1-Methoxy-2-propanol: 48.18 parts by mass    -   2-Butyrolactone: 13.77 parts by mass    -   2-Butanone: 61.94 parts by mass

Pigment 1 is a mixture consisting of the above-described components (apigment, a polymer, and a dispersant). Disperbyk 167 is a dispersantavailable from BYK Chemie GmbH.

SR-399: Dipentaerythritol pentaacrylate (manufactured by Sartomer JapanInc.)

NK-Ester A-DPH: Dipentaerythritol hexaacrylate (manufactured byShin-Nakamura Chemical Co., Ltd.)

CD9053: Acid-modified acrylate (trifunctional) (manufactured by SartomerJapan Inc.)

Fluor N2900: surfactant (available from Cytonix Corporation)

PHOSMER PE (manufactured by Uni-chemical Co., Ltd.): the followingstructure

<Formation of Image Recording Layer 5>

The support was bar-coated with an image recording layer coatingsolution (5) having the following composition and dried in an oven at90° C. for 60 seconds, thereby forming an image recording layer 5 havinga thickness of 1.3 μm.

<Image Recording Layer Coating Solution (5)>

-   -   Binder polymer (4) (described above): 0.23 parts by mass    -   Urethane methacrylate oligomer (formed by reacting glycerol        dimethyl acrylate, glycerol monomethyl acrylate, propylene        glycol methacrylate, and hexamethylene diisocyanate): 0.38 parts        by mass    -   Ethoxylated bisphenol A diacrylate (manufactured by        Shin-Nakamura Chemical Co., Ltd.: NK ESTER BPE500): 0.06 parts        by mass    -   Polymerization initiator (5) (the following structure): 0.07        parts by mass    -   Sensitizing dye (5) (the following structure): 0.04 parts by        mass    -   Chain transfer agent (mercaptobenzothiazole): 0.005 parts by        mass    -   Pigment (polymer dispersion of Heliogen Blue 7565): 0.038 parts        by mass    -   Surfactant (manufactured by BYK Chemie GmbH: BYK307): 0.002        parts by mass    -   Phenoxyethanol: 10.35 parts by mass    -   Acetone: 1.15 parts by mass

<Formation of Image Recording Layer 6>

A water-based coating solution for an image recording layer containingcomponents such as the thermoplastic resin particles and the infraredabsorbing agent shown below was prepared, and the pH thereof wasadjusted to 3.6, the support was coated with the coating solution, anddried at 50° C. for 1 minute, thereby forming an image recording layer 6having a thickness of 0.69 μm.

(Components in Water-Based Coating Solution for Image Recording Layer)

-   -   Thermoplastic resin particles (styrene/acrylonitrile copolymer        (molar ratio of 50/50), average particle diameter: 61 nm):        coating amount: 0.6927 (g/m²)    -   Polyacrylic acid (Mw: 250000): coating amount: 0.09 (g/m²)    -   Surfactant (Zonyl FSO100, manufactured by DuPont): coating        amount: 0.0075 (g/m²)    -   Infrared absorbing agent IR-01 (the following structure, Et        represents an ethyl group): coating amount: 1.03×10⁻⁴ (mol/m²)

<Formation of Image Recording Layer 7>

The undercoat layer was coated with an image recording layer coatingsolution (7) having the following composition using a wire bar and driedat 115° C. for 34 seconds using a warm air dryer, thereby forming animage recording layer 7 having a thickness of 1 μm.

(Image Recording Layer Coating Solution (7))

-   -   Methyl ethyl ketone: 2.887 g    -   1-Methoxy-2-propanol: 3.275 g    -   Methanol 1.176 g    -   Binder polymer 1 (the following structure): 0.066 g    -   Binder polymer 2 (the following structure): 0.079 g    -   Binder polymer 3 (the following structure, 30 mass % solution in        methyl ethyl ketone): 0.350 g    -   Binder polymer 4 (the following structure, 9.5 mass % solution        in methyl ethyl ketone/cyclohexanone): 0.350 g    -   Polymerizable compound (the following structure, 85 mass %        solution in 1-methoxy-2-propanol): 0.463 g    -   Infrared absorbing agent (the following structure): 0.024 g    -   Polymerization initiator 1 (the following structure): 0.090 g    -   Polymerization initiator 2 (the following structure): 0.064 g    -   Sensitizing assistant (the following structure): 0.074 g    -   Polymerization inhibitor (the following structure): 0.001 g    -   Mercapto compound (the following structure): 0.023 g    -   Additive 1 (the following structure): 0.025 g        -   Fluorine-based surfactant (the following structure, MEGAFACE            F-780-F, manufactured by DIC Corporation, 10 mass % solution            in methyl ethyl ketone): 0.010 g    -   Pigment dispersion (the following structure, concentration of        solid contents: 22.5% by mass, methyl ethyl ketone: 31% by mass,        1-methoxy-2-propanol: 31% by mass, methanol: 15.5% by mass):        0.490 g

<Formation of Non-Photosensitive Layer 8>

The undercoat layer was bar-coated with a non-photosensitive layercoating solution (8) having the following composition and dried at 100°C. for 60 seconds, thereby forming a non-photosensitive layer 8 having athickness of 0.5 μm.

(Non-Photosensitive Layer Coating Solution (8))

-   -   Binder polymer A (the following structure): 2.465 parts by mass    -   Phosphoric acid (85 mass % aqueous solution): 0.08 parts by mass    -   Sulfophthalic acid (50 mass % aqueous solution): 0.017 parts by        mass    -   Tricarballylic acid: 0.017 parts by mass    -   Colorant (VPB-Naps (naphthalene sulfonate of Victoria Pure Blue,        manufactured by Hodogaya Chemical Co., Ltd.): 0.0014 parts by        mass    -   Fluorine-based surfactant (MEGAFACE F-780-F, manufactured by DIC        Corporation, 30 mass % solution in MEK): 0.009 parts by mass    -   Methyl ethyl ketone (MEK): 7.93 parts by mass    -   Methanol: 6.28 parts by mass    -   1-Methoxy-2-propanol (MFG): 2.01 parts by mass

The binder polymer A is a 16 mass % solution containing MFG/MEK at aratio of 1/1 of a condensation reaction product (mass average molecularweight: 85000, acid content: 1.64 meq/g) of four types of monomers (1)to (4) described below.

(1) 4,4-Diphenylmethane diisocyanate: 37.5% by mole

(2) Hexamethylene diisocyanate: 12.5% by mole

(3) 2,2-Bis(hydroxymethyl)propionic acid: 32.5% by mole

(4) Tetraethylene glycol: 17.5% by mole

<Formation of Image Recording Layer 9>

The undercoat layer was bar-coated with an image recording layer coatingsolution (9) having the following composition and dried in an oven at100° C. for 60 seconds, thereby forming an image recording layer 9having a thickness of 1.2 μm.

The image recording layer coating solution (9) was obtained by mixing aphotosensitive solution (3) and a microgel solution (4) described belowimmediately before the coating and then stirring the solution.

(Photosensitive Solution (3))

-   -   Binder polymer (6) 23 mass % 1-methoxy-2-propanol solution (the        following structure, Mw: 35000, n (number of ethylene oxide (EO)        repeating units): 0.300 parts    -   Binder polymer (7) 23 mass % 1-methoxy-2-propanol solution (the        following structure, Mw: 15000, n (number of ethylene oxide (EO)        repeating units): 0.450 parts    -   Infrared absorbing agent (1) (the following structure): 0.0306        parts    -   Borate compound (1) (Sodium tetraphenyl borate): 0.0135 parts    -   Polymerization initiator (1) (the following structure): 0.2113        parts    -   Polymerizable compound (1) (tris(acryloyloxyethyl) isocyanurate,        NK ESTER A-9300, 40% 2-butanone solution, manufactured by        Shin-Nakamura Chemical Co., Ltd.): 0.2875 parts        -   Low-molecular-weight hydrophilic compound (1)            (tris(2-hydroxyethyl)isocyanurate): 0.0287 parts    -   Low-molecular-weight hydrophilic compound (2)        (trimethylglycine): 0.0147 parts    -   Ultraviolet absorbing agent (1) (TINUVIN405, manufactured by        BASF SE) (the following structure): 0.04 parts    -   Fluorine-based surfactant (1) (the following structure): 0.004        parts    -   Phosphonium compound (1) (the following structure): 0.020 parts    -   Antioxidant 2,5-di-t-pentylhydroquinone (the following        structure): 0.008 parts    -   Polymerization inhibitor 4-methoxy-1-naphthol (the following        structure): 0.004 parts    -   2-Butanone: 5.346 parts    -   1-Methoxy-2-propanol: 3.128 g    -   Methanol: 0.964 parts    -   Pure water: 0.036 parts

<Synthesis of Binder Polymer (6)>

78.0 g of 1-methoxy-2-propanol was weighed in a three-neck flask andheated to 70° C. in a nitrogen stream. A mixed solution consisting of52.1 g of BLEMMER PME-100 (methoxydiethylene glycol monomethacrylate,manufactured by NOF Corporation), 21.8 g of methyl methacrylate, 14.2 gof methacrylic acid, 2.15 g of hexakis(3-mercaptopropionicacid)dipentaerythritol, 0.38 g of V-601 (dimethyl2,2′-azobis(isobutyrate), manufactured by FUJIFILM Wako Pure ChemicalCorporation), and 54 g of 1-methoxy-2-propanol was added dropwise to thereaction container for 2 hours and 30 minutes. After the completion ofthe dropwise addition, the solution was heated to 80° C. and allowed tocontinuously react for 2 hours. A mixed solution consisting of 0.04 g ofV-601 and 4 g of 1-methoxy-2-propanol was added thereto, and theresulting solution was heated to 90° C. and allowed to continuouslyreact for 2.5 hours. After the completion of the reaction, the reactionsolution was cooled to room temperature.

137.2 g of 1-methoxy-2-propanol, 0.24 g of4-hydroxytetramethylpiperidine-N-oxide, 26.0 g of glycidyl methacrylate,and 3.0 g of tetraethylammonium bromide were added to the reactionsolution, and the resulting solution was sufficiently stirred and heatedat 90° C.

After 18 hours, the reaction solution was cooled to room temperature(25° C.) and diluted with 99.4 g of 1-methoxy-2-propanol.

The concentration of solid contents in the binder polymer (6) which hadbeen obtained in the above-described manner was 23% by mass, and theweight-average molecular weight thereof in terms of polystyrene whichhad been measured by GPC was 35000.

<Synthesis of Binder Polymer (7)>

78.00 g of 1-methoxy-2-propanol was weighed in a three-neck flask andheated to 70° C. in a nitrogen stream. A mixed solution consisting of52.8 g of BLEMMER PME-100 (methoxydiethylene glycol monomethacrylate,manufactured by NOF Corporation), 2.8 g of methyl methacrylate, 25.0 gof methacrylic acid, 6.4 g of hexakis(3-mercaptopropionicacid)dipentaerythritol, 1.1 g of V-601 (dimethyl2,2′-azobis(isobutyrate), manufactured by FUJIFILM Wako Pure ChemicalCorporation), and 55 g of 1-methoxy-2-propanol was added dropwise to thereaction container for 2 hours and 30 minutes. After the completion ofthe dropwise addition, the solution was heated to 80° C. and allowed tocontinuously react for 2 hours. After 2 hours, a mixed solutionconsisting of 0.11 g of V-601 and 1 g of 1-methoxy-2-propanol was addedthereto, and the resulting solution was heated to 90° C. and allowed tocontinuously react for 2.5 hours. After the completion of the reaction,the reaction solution was cooled to room temperature.

177.2 g of 1-methoxy-2-propanol, 0.28 g of4-hydroxytetramethylpiperidine-N-oxide, 46.0 g of glycidyl methacrylate,and 3.4 g of tetrabutylammonium bromide were added to the reactionsolution, and the resulting solution was sufficiently stirred and heatedat 90° C.

After 18 hours, the reaction solution was cooled to room temperature(25° C.) and diluted with 0.06 g of 4-methoxyphenol and 114.5 g of1-methoxy-2-propanol.

The concentration of solid contents in the binder polymer (7) which hadbeen obtained in the above-described manner was 23% by mass, and theweight-average molecular weight thereof in terms of polystyrene whichhad been measured by GPC was 15000.

(Microgel Solution (4))

-   -   Microgel (4) (concentration of solid contents: 21.8% by mass):        2.243 parts    -   1-Methoxy-2-propanol: 0.600 parts

A method of preparing a microgel (4) used in the microgel solution (4)will be described below.

<Preparation of Polyvalent Isocyanate Compound (1)>

0.043 parts of bismuth tris(2-ethylhexanoate) (NEOSTANN U-600(manufactured by NITTO KASEI CO., LTD.)) was added to an ethyl acetate(25.31 parts) suspension solution of 17.78 parts (80 molar equivalent)of isophorone diisocyanate and 7.35 parts (20 molar equivalent) of thefollowing polyhydric phenol compound (1), and the resulting solution wasstirred. The reaction temperature was set to 50° in a case of heatgeneration being subsided, and the solution was stirred for 3 hours,thereby obtaining an ethyl acetate (50% by mass) solution of apolyvalent isocyanate compound (1).

<Preparation of Microgel (4)>

The oil phase components and the water phase components were mixed witheach other and emulsified at 12000 rpm for 10 minutes using ahomogenizer. The obtained emulsion was stirred at 45° C. for 4 hours,5.20 parts of a 10 mass % aqueous solution of1,8-diazabicyclo[5.4.0]undeca-7-ene-octylate (U-CAT SA102, manufacturedby San-Apro Ltd.) was added thereto, and the solution was stirred atroom temperature for 30 minutes and allowed to stand at 45° C. for 24hours. The concentration of solid contents was adjusted to 21.8% by massusing distilled water, thereby obtaining an aqueous dispersion liquid ofthe microgel (4). The volume average particle diameter was measuredusing a dynamic light scattering type particle size distributionmeasuring device LB-500 (manufactured by Horiba Ltd.) according to alight scattering method, and the value was 0.28 μm.

(Oil Phase Components)

(Component 1) ethyl acetate: 12.0 parts

(Component 2) adduct (50 mass % ethyl acetate solution, manufactured byMitsui Chemicals, Inc.) obtained by adding trimethylolpropane (6 mol)and xylene diisocyanate (18 mol) and adding methyl one-terminalpolyoxyethylene (1 mol, repetition number of oxyethylene units: 90)thereto: 3.76 parts

(Component 3) polyvalent isocyanate compound (1) (as 50 mass % ethylacetate solution): 15.0 parts

(Component 4) 65 mass % solution of dipentaerythritol pentaacrylate(SR-399, manufactured by Sartomer Japan Inc.) in ethyl acetate: 11.54parts

(Component 5) 10% solution of sulfonate type surfactant (PIONINE A-41-C,manufactured by TAKEMOTO OIL & FAT Co., Ltd.) in ethyl acetate: 4.42parts

(Water Phase Components)

Distilled water: 46.87 parts

<Formation of Protective Layer 1>

The image recording layer was bar-coated with a protective layer coatingsolution (1) having the following composition and dried in an oven at120° C. for 60 seconds, thereby forming a protective layer 1 having thethickness listed in Table A.

(Protective Layer Coating Solution (1))

-   -   Polyvinyl alcohol (POVAL PVA105, manufactured by Kuraray Co.,        Ltd.): 0.6 parts by mass    -   Polyethylene glycol (PEG4000, manufactured by Tokyo Chemical        Industry Co., Ltd.): 0.39 parts by mass    -   Surfactant (RAPISOL A-80 (described below), manufactured by NOF        Corporation): 0.01 parts by mass    -   Water: 9 parts by mass

<Formation of Protective Layer 2>

The image recording layer was bar-coated with a protective layer coatingsolution (2) having the following composition and dried in an oven at120° C. for 60 seconds, thereby forming a protective layer 2 having thethickness listed in Table A.

(Protective Layer Coating Solution (2))

-   -   Inorganic layered compound dispersion liquid (1) (described        below): 1.5 parts    -   Hydrophilic polymer (1) (the following structure, Mw: 30000)        (solid content): 0.03 parts    -   Polyvinyl alcohol (CKS50, manufactured by Nippon Synthetic        Chemical Industry Co., Ltd., sulfonic acid-modified,        saponification degree of 99% by mole or greater, degree of        polymerization of 300), 6 mass % aqueous solution: 0.10 parts    -   Polyvinyl alcohol (PVA-405, manufactured by Kuraray Co., Ltd.,        saponification degree of 81.5% by mole, degree of polymerization        of 500), 6 mass % aqueous solution: 0.03 parts    -   Surfactant (EMALEX 710, manufactured by Nihon Emulsion Co.,        Ltd., the following structure), 1 mass % aqueous solution: 0.86        parts    -   Ion exchange water: 6.0 parts

The numbers on the lower right side of the parentheses of eachconstitutional unit in hydrophilic polymer (1) indicate the molarratios.

(Preparation of Inorganic Layered Compound Dispersion Liquid (1))

6.4 parts of synthetic mica SOMASIF ME-100 (manufactured by CO-OPCHEMICAL CO., LTD.) was added to 193.6 g of ion exchange water anddispersed therein such that the volume average particle diameter (laserscattering method) was set to 3 μm using a homogenizer, therebypreparing an inorganic layered compound dispersion liquid (1). Theaspect ratio of the dispersed particles was 100 or greater.

<Formation of Protective Layer 3>

The image recording layer was bar-coated with a protective layer coatingsolution (3) having the following composition and dried in an oven at120° C. for 60 seconds, thereby forming a protective layer 3 having thethickness listed in Table A.

(Protective Layer Coating Solution (3))

-   -   Polyvinyl alcohol (PVA-405, manufactured by Kuraray Co., Ltd.,        saponification degree of 81.5% by mole, degree of        polymerization: 500), 6 mass % aqueous solution: 66.33 parts by        mass    -   Surfactant (Masurf 1520, manufactured by Pilot Chemical Corp.):        0.02 parts by mass    -   Ion exchange water: 8.65 parts by mass

<Formation of Protective Layer 4>

The image recording layer was bar-coated with a protective layer coatingsolution (4) having the following composition and dried in an oven at125° C. for 70 seconds, thereby forming a protective layer 4 having thethickness listed in Table A.

(Protective Layer Coating Solution (4))

-   -   PVA-1 (GOHSELAN L-3266, manufactured by Nippon Synthetic        Chemical Industry Co., Ltd.): 0.61 parts by mass    -   PVA-2 (NICHIGO G-Polymer AZF8035, manufactured by Nippon        Synthetic Chemical Industry Co., Ltd.): 0.32 parts by mass    -   Surfactant (EMALEX 710, manufactured by Nihon Emulsion Co.,        Ltd.): 0.002 parts by mass    -   Water: 13 parts by mass

<Formation of Lower Protective Layer 5A>

The image recording layer was coated with a protective layer coatingsolution (5A) having the following composition using a wire bar anddried at 125° C. for 60 seconds using a warm air dryer, thereby forminga protective layer 5A having the thickness listed in Table A.

<Protective Layer Coating Solution (5A)>

-   -   Synthetic mica dispersion liquid (SOMASIF MEB-3L, manufactured        by CO-OP CHEMICAL CO., LTD., 3.2% aqueous dispersion liquid):        0.578 g    -   Polyvinyl alcohol (CKS-50, manufactured by Nippon Synthetic        Chemical Industry Co., Ltd., saponification degree of 99% by        mole, degree of polymerization of 300): 0.426 g    -   Acrylic binder (the following structure, 13 mass % aqueous        solution): 0.095 g    -   Surfactant 1 (PLURONIC P-84, manufactured by BASF SE): 0.07 g    -   Surfactant 2 (EMALEX 710, manufactured by Nihon Emulsion Co.,        Ltd.): 0.02 g    -   Pure water: 10.27 g

<Formation of Upper Protective Layer 5B>

The lower protective layer 5A was coated with a protective layer coatingsolution (5B) having the following composition using a wire bar anddried at 125° C. for 75 seconds using a warm air dryer, thereby forminga protective layer 5B having the thickness listed in Table A.

<Protective Layer Coating Solution (5B)>

-   -   Synthetic mica (SOMASIF MEB-3L, manufactured by CO-OP CHEMICAL        CO., LTD., 3.2% aqueous dispersion liquid): 1.024 g    -   Polyvinyl alcohol (GOHSELAN L-3266, manufactured by Nippon        Synthetic Chemical Industry Co., Ltd., saponification degree of        85% by mole, degree of polymerization of 300): 1.397 g    -   Carboxymethyl cellulose (CELLOGEN FS-B, manufactured by DKS Co.,        Ltd.): 0.215 g    -   Surfactant 2 (EMALEX 710, manufactured by Nihon Emulsion Co.,        Ltd.): 0.048 g    -   Silica-coated acrylic resin particles (ART PEARL J-7P,        manufactured by Negami Chemical Industrial Co., Ltd.): 0.054 g    -   Pure water: 41.42 g

<Formation of Protective Layer 6>

The non-photosensitive layer 8 was bar-coated with a protective layercoating solution (6) having the following composition and dried at 125°C. for 75 seconds, thereby forming a protective layer 6 having thethickness listed in Table A.

(Protective Layer Coating Solution (6))

-   -   Synthetic mica (SOMASIF ME-100, manufactured by CO-OP CHEMICAL        CO., LTD., 8% aqueous dispersion liquid): 94 parts by mass    -   Polyvinyl alcohol (CKS-50, manufactured by Nippon Synthetic        Chemical Industry Co., Ltd., saponification degree of 99% by        mole, degree of polymerization of 300): 58 parts by mass    -   Carboxymethyl cellulose (CELLOGEN PR, manufactured by DKS Co.,        Ltd.): 24 parts by mass    -   Surfactant-1 (PLURONIC P-84, manufactured by BASF SE): 2.5 parts        by mass    -   Surfactant-2 (EMALEX 710, manufactured by Nihon Emulsion Co.,        Ltd.): 5 parts by mass    -   Pure water: 1364 parts by mass

PLURONIC P-84 is an ethylene oxide/propylene oxide block copolymer, andEMALEX 710 is polyoxyethylene lauryl ether.

<Formation of Protective Layer 7>

The undercoat layer was bar-coated with a protective layer coatingsolution (7) having the following composition and dried in an oven at120° C. for 60 seconds, thereby forming a protective layer 7 having thethickness listed in Table A.

(Protective Layer Coating Solution (7))

-   -   Polyvinyl alcohol (GOHSELAN L-3266, manufactured by Nippon        Synthetic Chemical Industry Co., Ltd., sulfonic acid-modified,        saponification degree of 85% by mole, 6 mass % aqueous        solution): 0.501 parts    -   Surfactant (PIONINE A-32-B (the following structure),        manufactured by TAKEMOTO OIL & FAT Co., Ltd., 40 mass % aqueous        solution): 0.015 parts    -   Fluorine-based surfactant (1) (described above): 0.060 parts    -   Ammonium dihydrogen phosphate: 0.089 parts    -   Anionic surfactant 1 (the following structure), 30 mass %        aqueous solution: 0.140 parts    -   Pure water: 18.413 parts

<Formation of Protective Layer 8>

The support was coated with a protective layer coating solution (8)having the following composition using a wire bar and dried at 125° C.for 75 seconds, thereby forming a protective layer 8 having thethickness listed in Table A.

(Protective Layer Coating Solution (8))

-   -   Resin P (the following structure): 0.30 g    -   Pure water: 5.20 g    -   Methanol: 2.00 g

<Formation of Protective Layer 9>

The image recording layer was bar-coated with a protective layer coatingsolution (9) having the following composition and dried in an oven at120° C. for 60 seconds, thereby forming a protective layer 9 having thethickness listed in Table A.

(Protective Layer Coating Solution (9))

-   -   Inorganic layered compound dispersion liquid (1) (described        above): 2.876 parts    -   Polyvinyl alcohol (GOHSELAN L-3266, manufactured by Nippon        Synthetic Chemical Industry Co., Ltd., sulfonic acid-modified,        saponification degree of 85% by mole, 6 mass % aqueous        solution): 0.112 parts    -   Surfactant (PIONINE A-32-B (described above), manufactured by        TAKEMOTO OIL & FAT Co., Ltd., 40 mass % aqueous solution): 0.018        parts    -   Surfactant (SURFYNOL 465 (the following structure), manufactured        by Nissin Chemical Co., Ltd.): 0.007 part    -   Phosphoric acid (85 mass % aqueous solution): 0.027 parts    -   Diammonium hydrogen phosphate: 0.038 parts    -   Anionic surfactant 1 (described above), 30 mass % aqueous        solution: 0.140 parts    -   Pure water: 4.519 parts

<Formation of Uneven Shape on Outermost Layer>

An uneven shape was formed on the outermost layer at the side where theimage recording layer was provided as listed in Table A using thefollowing particle coating method or protrusion forming method as unevenshape forming means.

(Particle Coating Method (Particles))

The particles listed in Table A were added to the coating solutiondescribed in the unevenness formation position listed in Table A suchthat the addition amount thereof was adjusted to obtain the in-planedensity listed in Table A, thereby coating the particles with thesolution.

The “ART PEARL” particles in Table A are acrylic resin particles(manufactured by Negami Chemical Industrial Co., Ltd.).

(Protrusion Forming Method (Protrusion))

A polyvinyl alcohol (PVA, manufactured by Kuraray Co., Ltd., POVALPVA405) aqueous solution or a sodium polyacrylate (manufactured byFUJIFILM Wako Pure Chemical Corporation) aqueous solution was preparedsuch that the concentration of solid contents was set to 5.0% by mass,and the surface of the protective layer was coated with the solutionaccording to a rotary atomization electrostatic coating method and driedat 100° C. for 30 seconds.

<Formation of Back Coat Layer 1>

The surface of the support at the side opposite to the side where theprotective layer was provided was coated with a back coat layer coatingsolution (1) having the following composition and dried at 100° C. for30 seconds, thereby forming a back coat layer 1.

(Back Coat Layer Coating Solution (1))

-   -   Poly(methyl methacrylate) (Mw: 120000, manufactured by        Sigma-Aldrich Co. LLC.): 10.0 parts by mass    -   Fluorine-based surfactant (1) (described above): 0.05 parts by        mass    -   Methyl ethyl ketone: 90.0 parts by mass    -   ART PEARL J-6P: 0.13 parts by mass

<Formation of Back Coat Layer 2>

The surface of the support at the side opposite to the side where theprotective layer was provided was bar-coated with a back coat layercoating solution (2) having the following composition and dried at 100°C. for 120 seconds, thereby forming a back coat layer 2 having athickness of 0.3 μm.

(Preparation of Back Coat Layer Coating Solution (2))

-   -   Tetraethyl silicate (metal oxide): 50 parts by mass    -   Water: 20 parts by mass    -   Methanol: 15 parts by mass    -   Phosphoric acid: 0.05 parts by mass

In a case where the above-described components were mixed and stirred,heat was generated in approximately 5 minutes. After the reaction for 60minutes, a back coat layer coating solution (2) was prepared by addingthe following mixed solution thereto.

-   -   Pyrogallol formaldehyde condensation resin (Mw: 2000): 4 parts        by mass        -   Dimethyl phthalate: 5 parts by mass            -   Fluorine-based surfactant (N-butyl perfluorooctane                sulfonamide ethyl acrylate/polyoxyethylene acrylate                copolymer (Mw: 20000): 0.7 parts by mass        -   Methanol: 800 parts by mass

<Preparation of Planographic Printing Plate Precursor>

The support, the undercoat layer, the image recording layer or thenon-photosensitive layer, the protective layer, and the back coat layerwere combined as listed in Table A, to prepare a planographic printingplate precursor. In the planographic printing plate precursors ofExamples 1 to 39 and Comparative Examples 1 to 6, the Bekk smoothness ofthe surface of the outermost layer at the side opposite to the sidewhere the image recording layer was provided was 1200 seconds, and thearithmetic average height Sa was 0.1 μm. In the planographic printingplate precursor of Example 40, the Bekk smoothness of the surface of theoutermost layer at the side opposite to the side where the imagerecording layer was provided was 80 seconds, and the arithmetic averageheight Sa was 2.1 μm. In the planographic printing plate precursors ofExamples 41 to 45, the Bekk smoothness of the surface of the outermostlayer at the side opposite to the side where the image recording layeror the non-photosensitive layer was provided was 1240 seconds, and thearithmetic average height Sa was 0.1 μm.

TABLE 7 Image Total Total recording In-plane value value layerProtective density Arith- of of or non- layer/ Uneven- Uneven- of Bekkmetic Bekk arith- Under- photo- thick- ness ness particles smooth-average Back smooth- metic coat sensitive ness forming forming(particles/ ness height coat ness average Support layer layer (μm) meansposition mn²) (sec) (μm) layer) reciprocals heights Example 1 1 — 11/0.8 Particles 1 Protective 1000 210 0.4 — 0.00560 0.5 layer Example 21 — 1 1/0.8 Particles 2 Protective 1000  95 1.0 — 0.01136 1.1 layerExample 3 1 — 1 1/0.8 Particles 3 Protective 1000  23 2.5 — 0.04431 2.6layer Example 4 1 — 1 1/0.8 Particles 4 Protective 1000  8 4.5 — 0.125834.6 layer Example 5 1 — 1 1/0.8 Particles 5 Protective 1000  5 7.0 —0.20083 7.1 layer Example 6 1 — 1 1/0.2 Particles 3 Protective 1000  192.7 — 0.05346 2.8 layer Example 7 1 — 1 1/1   Particles 3 Protective1000  38 2.1 — 0.02715 2.2 layer Example 8 1 — 1 1/2   Particles 3Protective 1000  47 1.9 — 0.02211 2.0 layer Example 9 1 — 1 1/3  Particles 3 Protective 1000  55 1.4 — 0.01902 1.5 layer Example 10 1 — 11/0.8 Particles 3 Protective  100  45 2.0 — 0.02306 2.1 layer Example 111 — 1 1/0.8 Particles 3 Protective  500  34 2.4 — 0.03025 2.5 layerExample 12 1 — 1 1/0.8 Particles 3 Protective 5000  19 3.0 — 0.05346 3.1layer Example 13 1 — 1 1/0.8 Particles 1 Image 1000 250 0.3 — 0.004830.4 forming layer Example 14 1 — 1 1/0.8 Particles 2 Image 1000 154 0.8— 0.00733 0.9 forming layer Example 15 1 — 1 1/0.8 Particles 3 Image1000  29 2.3 — 0.03532 2.4 forming layer Example 16 1 — 1 1/0.8Particles 4 Image 1000  9 3.9 — 0.11194 4.0 forming layer Example 17 1 —1 1/0.8 Particles 3 Image  100  58 1.7 — 0.01807 1.8 forming layerExample 18 1 — 1 1/0.8 Particles 3 Image  500  40 2.1 — 0.02583 2.2forming layer Example 19 1 — 1 1/0.8 Particles 3 Image 5000  24 2.8 —0.04250 2.9 forming layer Example 20 2 1 2 2/0.2 Particles 3 Image 1000 46 1.2 — 0.02257 1.3 forming layer Example 21 2 1 2 2/0.2 Particles 3Protective 1000  20 2.8 — 0.05083 2.9 layer Example 22 2 1 2 2/1  Particles 3 Protective 1000  25 2.5 — 0.04083 2.6 layer

TABLE 8 Image Total Total recording In-plane value value layerProtective density Arith- of of or non- layer/ Uneven- Uneven- of Bekkmetic Bekk arith- Under- photo- thick- ness ness particles smooth-average Back smooth- metic coat sensitive ness forming forming(particles/ ness height coat ness average Support layer layer (μm) meansposition mn²) (sec) (μm) layer) reciprocals heights Example 23  1 — 11/0.8 Protrusion On — 72 2.3 — 0.01472 2.4 1 protective layer Example 24 1 — 1 1/0.8 Protrusion On —  6 9.9 — 0.16750 10.0  1 protective layerExample 25  1 — 1 1/0.8 Protrusion On —  7 9.6 — 0.14369 9.7 2protective layer Example 26  2 1 2 2/1   Protrusion On —  8 9.6 —0.12583 9.7 1 protective layer Example 27  3 — 1 1/0.8 Particles 3Protective 1000 23 2.5 — 0.04431 2.6 layer Example 28  1 — 1 1/0.8Particles 3 Protective 1000 23 2.5 — 0.04431 2.6 layer Example 29  4 — 11/0.8 Particles 3 Protective 1000 23 2.5 — 0.04431 2.6 layer Example 30 5 — 1 1/0.8 Particles 3 Protective 1000 23 2.5 — 0.04431 2.6 layerExample 31  6 — 1 1/0.8 Particles 3 Protective 1000 23 2.5 — 0.04431 2.6layer Example 32  7 — 1 1/0.8 Particles 3 Protective 1000 23 2.5 —0.04431 2.6 layer Example 33  8 — 1 1/0.8 Particles 3 Protective 1000 232.5 — 0.04431 2.6 layer Example 34  9 — 1 1/0.8 Particles 3 Protective1000 23 2.5 — 0.04431 2.6 layer Example 35 10 — 1 1/0.8 Particles 3Protective 1000 23 2.5 — 0.04431 2.6 layer Example 36 11 2 3 2/0.2Particles 3 Protective 1000 19 2.8 — 0.05346 2.9 layer Example 37 12 — 43/0.2 Particles 3 Protective 1000 23 2.5 — 0.04431 2.6 layer Example 3812 — 5 4/0.2 Particles 3 Protective 1000 23 2.5 — 0.04431 2.6 layerExample 39 13 — 6 1/0.8 Particles 1 Protective 1000 22 2.4 — 0.04629 2.5layer Example 40  1 — 1 1/0.8 Particles 4 Protective 1000 210  0.4 10.01726 2.5 5A/0.5 layer Example 41 14 3 7 5B/1.7 Particles 4 Protective1000 12 4.0 2 0.12583 4.1 layer 5B Example 42 14 4 8 6/1.6 Particles 3Protective 1000 23 2.2 2 0.04428 2.3 layer Example 43 15 5 - 7/0.6Particles 3 Protective 1000 20 2.6 2 0.05081 2.7 layer Example 44 15 — -8/0.3 Particles 3 Protective 1000 28 2.4 2 0.03652 2.5 layer Example 4515 5 9 9/0.3 Particles 3 Protective 1000 20 2.6 2 0.05081 2.7 layerComparative  1 — 1 1/0.8 Not Not 1100  0.1 — 0.00174 0.2 Example 1available available Comparative  1 — 1 1/0.1 Particles 3 Protective 100023 2.5 — 0.04431 2.6 Example 2 layer Comparative  1 — 1  1/0.05Particles 3 Protective 1000 23 2.5 — 0.04431 2.6 Example 3 layerComparative  1 — 1 1/0.1 Particles 5 Protective 1000  5 7.0 — 0.200837.1 Example 4 layer Comparative  1 — 1 Particles 3 Image 1000 22 2.6 —0.04629 2.7 recording Example 5 layer Comparative  1 — 1 1/0.1 Particles6 Protective 1000  2 22.0  — 0.50083 22.1  Example 6 layer

In Table A, “Particles 1” listed in the columns of the unevennessforming means indicate particles having a diameter of 1.9 μm (ART PEARLJ-4P), “Particles 2” indicate particles having a diameter of 3.2 μm (ARTPEARL J-5P), “Particles 3” indicates particles having a diameter of 5.3μm (ART PEARL J-6P, “Particles 4” indicate particles having a diameterof 6.5 μm (ART PEARL J-7PS), “Particles 5” indicate particles having adiameter of 10 μm (ART PEARL GR-600 transparent), and “Particles 6”indicate particles having a diameter of 32 μm (ART PEARL GR-200).

Further, “Protrusion 1” indicates an uneven shape formed using a PVAaqueous solution according to the protrusion forming method, and“Protrusion 2” indicates an uneven shape formed using a sodiumpolyacrylate aqueous solution according to the protrusion formingmethod.

The following evaluations were performed on the obtained planographicprinting plate precursors. The evaluation results are listed in Table B.

<Property of Preventing Development Delay>

(1) Planographic Printing Plate Precursor for On-Press Development(Planographic Printing Plate Precursors of Examples 1 to 35, 40, and 43to 45)

The surface of the planographic printing plate precursor where theprotective layer was provided was directly brought into contact with theopposite surface thereof and this process was repeated until a total of50 sheets were laminated, and the laminate was pressure-bonded by apressure of 25 kgf/cm² for 8 days. The planographic printing plateprecursor on which the operation had been performed was set byTrendsetter 3244 (manufactured by Creo Co., Ltd.) and then image-exposedunder conditions of a resolution of 2400 dpi, an output of 7 W, anexternal drum rotation speed of 150 rpm, and a plate surface energy of110 mJ/cm². Further, image exposure was not performed on the key plateprecursor. The planographic printing plate precursors after imageexposure were mounted on an offset rotary printing press (manufacturedby TOKYO KIKAI SEISAKUSHO, LTD.), and printing was performed onnewsprint paper at a speed of 100,000 sheets/hour using SOIBI KKST-S(red) (manufactured by InkTec Corporation) as printing ink for newspaperand ECO SEVEN N-1 (manufactured by SAKATA INX CORPORATION) as dampeningwater. The on-press development performed on the unexposed portion ofthe image recording layer on the printing press was completed, and thenumber of sheets of printing paper required until the ink was nottransferred to the non-image area was counted as the number of on-pressdevelopment sheets, and the property of preventing development delay wasevaluated based on the following evaluation standards. The acceptablerange is 3 to 5.

5: The number of on-press development sheets of planographic printingplate precursors on which the pressure bonding operation had not beenperformed+3 or less of on-press development sheets

4: The number of on-press development sheets of planographic printingplate precursors on which the pressure bonding operation had not beenperformed+4 or more of on-press development sheets of planographicprinting plate precursors on which the pressure bonding operation hadnot been performed+5 or less of on-press development sheets

3: The number of on-press development sheets of planographic printingplate precursors on which the pressure bonding operation had not beenperformed+6 or more of on-press development sheets of planographicprinting plate precursors on which the pressure bonding operation hadnot been performed+10 or less of on-press development sheets

2: The number of on-press development sheets of planographic printingplate precursors on which the pressure bonding operation had not beenperformed+11 or more of on-press development sheets of planographicprinting plate precursors on which the pressure bonding operation hadnot been performed+15 or less of on-press development sheets

1: The number of on-press development sheets of planographic printingplate precursors on which the pressure bonding operation was notperformed+16 or more of on-press development sheets

(2) Planographic Printing Plate Precursor for Development UsingDeveloper (Planographic Printing Plate Precursor of Example 36)

The surface of the planographic printing plate precursor where theprotective layer was provided was directly brought into contact with theopposite surface thereof and this process was repeated until a total of50 sheets were laminated, and the laminate was pressure-bonded by apressure of 25 kgf/cm² for 8 days. The planographic printing plateprecursor on which the above-described operation had been performed wasset by Luxel PLATESETTER T-6000III (manufactured by FujifilmCorporation) equipped with an infrared semiconductor laser and thenexposed under conditions of an external drum rotation speed of 1000 rpm(for each time), a laser output of 70%, and a resolution of 2400 dpi(dot per inch). A solid image and a 50% halftone dot chart were includedin the exposed image.

Next, the development treatment was performed using a developer 1 withthe following composition and an automatic development treatment devicehaving a structure illustrated in FIG. 4 , thereby obtaining aplanographic printing plate.

The development treatment device exemplified in FIG. 4 is an automaticdevelopment treatment device including two rotary brush rolls 111. Abrush roll having an external diameter of 55 mm in which polybutyleneterephthalate fibers (diameter of bristles: 200 mm, length of bristle: 7mm) were implanted was used as the rotary brush roll 111, and the rollwas allowed to rotate 120 times (the peripheral speed of the brush tip:0.94 m/s) per minute in the same direction as the transportationdirection.

A planographic printing plate precursor 130 after the exposure wascompleted was transported in the transportation direction illustrated inthe figure between two pairs of transport rolls 113 from a plate feedstand 118 to a plate discharge stand 119 at a transportation speed of 60cm/min on a transport guide plate 114 such that the planographicprinting plate precursor 130 was allowed to pass through a space betweenthe rotary brush roll 111 and the transport guide plate 114.

In three spray pipes 115, the developer stored in a developer tank 120was supplied by a circulation pump 121 through a filter 117 using a pipeline 116, and the developer was supplied to the plate surface from eachspray pipe 115 by performing showering. Further, the volume of thedeveloper tank 120 was 20 liters, and the developer was recycled. Theplanographic printing plate discharged from the development treatmentdevice was dried by a dryer 122 without being washed with water.

<Developer 1>

-   -   Surfactant-1 described below (PELEX NBL, manufactured by Kao        Corporation): 7.43 g    -   Surfactant-2 described below (NEWCOL B13, manufactured by Nippon        Nyukazai Co., Ltd.): 1.45 g    -   Surfactant-3 described below (SURFYNOL 2502, manufactured by Air        Products and Chemicals, Inc.): 0.4 g    -   Benzyl alcohol: 0.6 g    -   Sodium gluconate: 2.77 g    -   Disodium monohydrogen phosphate: 0.3 g    -   Sodium hydrogen carbonate: 0.22 g    -   Antifoaming agent (SILCOLAPSE 432, manufactured by Bluestar        Silicones): 0.005 g    -   Water: 86.83 g    -   pH: 8.5

Each of the obtained planographic printing plates having a size of 5cm×5 cm was observed using a 25 magnification loupe, the number ofresidual films was counted, and the property of preventing developmentdelay was evaluated based on the following standards. The acceptablerange is 3 to 5.

5: The number of residual films was 0.

4: The number of residual films was 1 or 2.

3: The number of residual films was in a range of 3 to 10.

2: The number of residual films was in a range of 11 to 50.

1: The number of residual films was greater than 50.

(3) Planographic Printing Plate Precursor for Development UsingDeveloper (Planographic Printing Plate Precursor of Example 37)

The surface of the planographic printing plate precursor where theprotective layer was provided was directly brought into contact with theopposite surface thereof and this process was repeated until a total of50 sheets were laminated, and the laminate was pressure-bonded by apressure of 25 kgf/cm² for 8 days. The planographic printing plateprecursor on which the above-described operation had been performed wasimage-exposed and subjected to the development treatment in the samemanner as that for (2) planographic printing plate precursor fordevelopment using the developer described above, thereby obtaining aplanographic printing plate. Here, a developer 2 described below wasused as the developer. With respect to the obtained planographicprinting plate, the property of preventing development delay wasevaluated in the same manner as that for (2) planographic printing plateprecursor for development using the developer described above.

<Developer 2>

-   -   2-Phenoxyethanol: 5.0 parts by mass    -   Surfactant (PELEX NBL, manufactured by Kao Corporation): 5.0        parts by mass    -   Surfactant (NEWCOL B13, manufactured by Nippon Nyukazai Co.,        Ltd.): 5.0 parts by mass    -   Diethanolamine: 4.0 parts by mass    -   Water: 81.0 parts by mass    -   pH: 10.5

(4) Planographic Printing Plate Precursor for Development UsingDeveloper (Planographic Printing Plate Precursor of Example 38)

The surface of the planographic printing plate precursor where theprotective layer was provided was directly brought into contact with theopposite surface thereof and this process was repeated until a total of50 sheets were laminated, and the laminate was pressure-bonded by apressure of 25 kgf/cm² for 8 days. The planographic printing plateprecursor on which the above-described operation had been performed wasimage-exposed and subjected to the development treatment in the samemanner as that for (2) planographic printing plate precursor fordevelopment using the developer described above, thereby obtaining aplanographic printing plate. Here, a developer 3 described below wasused as the developer. With respect to the obtained planographicprinting plate, the property of preventing development delay wasevaluated in the same manner as that for (2) planographic printing plateprecursor for development using the developer described above.

<Developer 3>

-   -   Surfactant (PELEX NBL, manufactured by Kao Corporation): 7.14        parts by mass    -   Surfactant (NEWCOL B13, manufactured by Nippon Nyukazai Co.,        Ltd.): 7.5 parts by mass    -   Tristyrylphenol ethoxylate (Emulsogen TS160, manufactured by        Clariant): 2.5 parts by mass    -   Trisodium phosphate: 0.1 parts by mass    -   Glycine: 0.1 parts by mass    -   Water: 82.66 parts by mass    -   pH: 9.8

(5) Planographic Printing Plate Precursor for Development UsingDeveloper (Planographic Printing Plate Precursor of Example 39)

The surface of the planographic printing plate precursor where theprotective layer was provided was directly brought into contact with theopposite surface thereof and this process was repeated until a total of50 sheets were laminated, and the laminate was pressure-bonded by apressure of 25 kgf/cm² for 8 days. The planographic printing plateprecursor on which the above-described operation had been performed wasimage-exposed and subjected to the development treatment in the samemanner as that for (2) planographic printing plate precursor fordevelopment using the developer described above, thereby obtaining aplanographic printing plate. Here, a developer 4 described below wasused as the developer. With respect to the obtained planographicprinting plate, the property of preventing development delay wasevaluated in the same manner as that for (2) planographic printing plateprecursor for development using the developer described above.

<Developer 4>

-   -   Surfactant-4 (DOWFAX3B2, manufactured by Dow Chemical Company)        (described below): 0.7 parts by mass    -   Ethylene glycol: 0.7 parts by mass    -   Dextrin (Amicol No. 1, manufactured by Nippon Starch Chemical        Co., Ltd.): 3.9 parts by mass    -   Monopotassium dihydrogen phosphate: 2.7 parts by mass    -   Potassium hydroxide: 0.7 parts by mass    -   Antifoaming agent (SILCOLAPSE 432, manufactured by Bluestar        Silicones): 0.005 parts by mass    -   Water: 91.30 parts by mass    -   pH: 7.0

(6) Planographic Printing Plate Precursors for Development UsingDeveloper (Planographic Printing Plate Precursors of Examples 41 and 42)

The surface of the planographic printing plate precursor where theprotective layer was provided was directly brought into contact with theopposite surface thereof and this process was repeated until a total of50 sheets were laminated, and the laminate was pressure-bonded by apressure of 25 kgf/cm² for 8 days. The planographic printing plateprecursor on which the above-described operation had been performed wasset by Luxel PLATESETTER T-6000III (manufactured by FujifilmCorporation) equipped with an infrared semiconductor laser and thenexposed under conditions of an external drum rotation speed of 1000 rpm(for each time), a laser output of 70%, and a resolution of 2400 dpi(dot per inch). A solid image and a 50% halftone dot chart were includedin the exposed image. Further, image exposure was not performed on thekey plate precursor.

Next, the development treatment was performed at a transport speed (linespeed) 2 m/min and a development temperature of 30° C. using anautomatic developing machine LP-1310HII (manufactured by FujifilmCorporation), thereby obtaining a planographic printing plate. A 1:4water diluent of DH-N (manufactured by Fujifilm Corporation) was used asa developer, and a 1:1.4 water diluent of FCT-421 (manufactured byFujifilm Corporation) was used as a development replenisher. Withrespect to the obtained planographic printing plate, the property ofpreventing development delay was evaluated in the same manner as thatfor (2) planographic printing plate precursor for development using thedeveloper described above.

<Property of Preventing Multiple Plates from being Fed>

A laminate obtained by stacking 100 sheets of planographic printingplate precursors directed to the same direction without usinginterleaving paper was set in a CTP plate setter “AMZI setter”(manufactured by NEC Engineering, Ltd.), and an operation of taking outone plate at a time from the uppermost portion of the laminate wascontinuously performed 100 times. The plate-separating property here wasevaluated based on the following standards. The acceptable range for theproperty of preventing multiple plates from being fed is 3 to 5.

5: The occurrence frequency of a phenomenon in which the next plate wasnot raised in a case of lifting up a plate was 100%.

4: The occurrence frequency of a phenomenon in which the next plate wasraised in a case of lifting up a plate and did not drop immediately was1% or less with respect to the whole operations.

3: The occurrence frequency of a phenomenon in which the next plate wasraised in a case of lifting up a plate and was not peeled off by thefirst operation of separating the plate was 1% or less with respect tothe whole operations.

2: The occurrence frequency of a phenomenon in which the next plate wasraised in a case of lifting up a plate and was not peeled off by thefirst operation of separating the plate was greater than 1% and 5% orless with respect to the whole operations.

1: The occurrence frequency of a phenomenon in which the next plate wasraised in a case of lifting up a plate and was not peeled off by thefirst operation of separating the plate was greater than 5% with respectto the whole operations.

<Property of Preventing Falling of Projection>

After the humidity of the planographic printing plate precursor wasadjusted in an environment of 25° C. at 60% RH for 2 hours, theplanographic printing plate precursor was punched into a size of 2.5cm×2.5 cm and attached to a continuous load type scratch resistancestrength tester TYPE-18 (manufactured by SHINTO Scientific Co., Ltd.),the rear surface of the planographic printing plate precursor which hadbeen punched was set to be brought into contact with the surface of theplanographic printing plate precursor which has not been punched, andseveral sites of the planographic printing plate precursor werescratched by applying a pressure of 0 gf to 1500 gf. The scratched rearsurface was observed visually and using a scanning electron microscope(SEM), and the level of falling of projections from the surface of theoutermost layer at the side where the image recording layer was providedwas evaluated based on the following standards. The acceptable range is3 to 5.

5: Falling of projections did not found at all.

4: Among 100 projections, 1 or more and less than 5 projections werefallen off.

3: Among 100 projections, 5 or more and less than 10 projections werefallen off.

2: Among 100 projections, 10 or more and less than 50 projections werefallen off.

1: Among 100 projections, 50 or more projections were fallen off.

<Property of Preventing Scratches>

(1) Planographic Printing Plate Precursor for On-Press Development

After the humidity of the planographic printing plate precursor wasadjusted in an environment of 25° C. at 60% RH for 2 hours, theplanographic printing plate precursor was punched into a size of 2.5cm×2.5 cm and attached to a continuous load type scratch resistancestrength tester TYPE-18 (manufactured by SHINTO Scientific Co., Ltd.),the rear surface of the planographic printing plate precursor which hadbeen punched was set to be brought into contact with the surface of theplanographic printing plate precursor which has not been punched, andseveral sites of the planographic printing plate precursor werescratched by applying a pressure of 0 gf to 1500 gf. The scratchedplanographic printing plate precursor was set by Trendsetter 3244(manufactured by Creo Co., Ltd.) and then image-exposed under conditionsof resolution of 2400 dpi, an output of 7 W, an external surface drumrotation speed of 150 rpm, and a plate surface energy of 110 mJ/cm². Theplanographic printing plate precursors after image exposure were mountedon an offset rotary printing press (manufactured by TOKYO KIKAISEISAKUSHO, LTD.), and printing was performed on newsprint paper at aspeed of 100,000 sheets/hour using SOIBI KKST-S (red) (manufactured byInkTec Corporation) as printing ink for newspaper and ECO SEVEN N-1(manufactured by SAKATA INX CORPORATION) as dampening water. In theprinting process, the 1000-th printed material was sampled, the degreeof damage and stains caused by scratches was visually observed using a 6magnification loupe, and the property of preventing scratches wasevaluated based on the following standards. The acceptable range is 3 to5.

5: Damage and stains were not able to be visually confirmed using a 6magnification loupe.

4: Although damage and stains were not visually confirmed, damage andstain which were able to be confirmed using a 6 magnification loupe werefound at one site.

3: Although damage and stains were not visually confirmed, damage andstains which were able to be confirmed using a 6 magnification loupewere found at several sites.

2: Damage and stains were able to be visually confirmed at severalsites.

1: Damage and stains were able to be visually confirmed on the entiresurface.

(2) Planographic Printing Plate Precursor for Development UsingDeveloper

After the humidity of the planographic printing plate precursor wasadjusted in an environment of 25° C. at 60% RH for 2 hours, theplanographic printing plate precursor was punched into a size of 2.5cm×2.5 cm and attached to a continuous load type scratch resistancestrength tester TYPE-18 (manufactured by SHINTO Scientific Co., Ltd.),the rear surface of the planographic printing plate precursor which hadbeen punched was set to be brought into contact with the surface of theplanographic printing plate precursor which has not been punched, andseveral sites of the planographic printing plate precursor werescratched by applying a pressure of 0 gf to 1500 gf. The scratchedplanographic printing plate precursor was set by Trendsetter 3244(manufactured by Creo Co., Ltd.) and then image-exposed under conditionsof resolution of 2400 dpi, an output of 7 W, an external surface drumrotation speed of 150 rpm, and a plate surface energy of 110 mJ/cm². Theimage-exposed planographic printing plate precursor was subjected to thedevelopment treatment according to the method described for theplanographic printing plate precursor for development using a developerused in the evaluation of the property of preventing development delay,thereby obtaining a planographic printing plate.

The obtained planographic printing plate was mounted on an offset rotaryprinting press (manufactured by TOKYO KIKAI SEISAKUSHO, LTD.), andprinting was performed on newsprint paper at a speed of 100000sheets/hour using SOIBI KKST-S (red) (manufactured by InkTecCorporation) as printing ink for newspaper and ECO SEVEN N-1(manufactured by SAKATA INX CORPORATION) as dampening water. In theprinting process, the 1000-th printed material was sampled, the degreeof damage and stains caused by scratches was visually observed using a 6magnification loupe, and the property of preventing scratches wasevaluated based on the following standards. The acceptable range is 3 to5.

5: Damage and stains were not able to be visually confirmed using a 6magnification loupe.

4: Although damage and stains were not visually confirmed, damage andstain which were able to be confirmed using a 6 magnification loupe werefound at one site.

3: Although damage and stains were not visually confirmed, damage andstains which were able to be confirmed using a 6 magnification loupewere found at several sites.

2: Damage and stains were able to be visually confirmed at severalsites.

1: Damage and stains were able to be visually confirmed on the entiresurface.

TABLE 9 Property of Property of preventing Property of preventingmultiple preventing Property of development plates from falling ofpreventing delay being fed projection scratches Example 1 5 3 5 5Example 2 5 4 5 5 Example 3 5 5 4 5 Example 4 4 5 4 5 Example 5 3 5 3 5Example 6 3 5 4 5 Example 7 5 5 4 5 Example 8 5 5 5 5 Example 9 5 4 5 5Example 10 5 5 4 5 Example 11 5 5 4 5 Example 12 4 5 4 5 Example 13 5 35 5 Example 14 5 3 5 5 Example 15 5 5 4 5 Example 16 4 5 4 5 Example 175 4 4 5 Example 18 5 5 4 5 Example 19 4 5 4 5 Example 20 3 5 4 5 Example21 3 5 4 5 Example 22 5 5 5 5 Example 23 5 4 5 5 Example 24 3 5 5 5Example 25 3 5 5 5 Example 26 3 5 5 5 Example 27 5 5 4 5 Example 28 5 54 5 Example 29 5 5 4 5 Example 30 5 5 4 5 Example 31 5 5 4 5 Example 325 5 4 5 Example 33 5 5 4 5 Example 34 5 5 4 5 Example 35 5 5 4 5 Example36 5 5 4 5 Example 37 5 5 5 5 Example 38 5 5 5 5 Example 39 5 5 4 5Example 40 5 5 5 5 Example 41 5 5 5 5 Example 42 5 5 5 5 Example 43 5 53 5 Example 44 5 5 3 5 Example 45 5 5 3 5 Comparative 5 1 5 5 Example 1Comparative 3 5 2 5 Example 2 Comparative 2 5 1 5 Example 3 Comparative1 5 1 5 Example 4 Comparative 2 5 3 2 Example 5 Comparative 1 5 1 5Example 6

Based on the results listed in Table B, it was clarified that allcharacteristics such as the property of preventing multiple plates frombeing fed, the property of preventing falling of a projection, theproperty of preventing scratches, and the property of preventingdevelopment delay of the planographic printing plate precursor accordingto the embodiment of the present invention were excellent even in thecase of elimination of interleaving paper. On the contrary, it was foundthat one or more of the characteristics of the planographic printingplate precursors for comparison were degraded.

In particular, in the planographic printing plate precursor for on-pressdevelopment according to the embodiment of the present invention, it ispossible to effectively prevent on-press development delay whileexcellently maintaining the property of preventing multiple plates frombeing fed, the property of preventing falling of a projection, and theproperty of preventing scratches.

INDUSTRIAL AVAILABILITY

According to the present invention, it is possible to provide aplanographic printing plate precursor in which all characteristics suchas a property of preventing multiple plates from being fed in a step oftaking out a precursor from a stack, a property of preventing falling ofa projection provided on a surface of an outermost layer of theprecursor, a property of preventing scratches caused by a projectionprovided on the surface of the outermost layer of the precursor, and aproperty of preventing development delay caused by a projection providedon the surface of the outermost layer of the precursor are excellenteven in a case of elimination of interleaving paper, a planographicprinting plate precursor laminate including the planographic printingplate precursor, a plate-making method for a planographic printingplate, and a planographic printing method.

Although the present invention has been described in detail withreference to particular embodiments, it will be apparent to thoseskilled in the art that various changes and modifications can be madewithout departing from the spirit and scope of the present invention.

EXPLANATION OF REFERENCES

-   -   50: main electrolytic cell    -   51: AC power source    -   52: radial drum roller    -   53 a, 53 b: main pole    -   54: electrolytic solution supply port    -   55: electrolytic solution    -   56: slit    -   57: electrolytic solution passage    -   58: auxiliary anode    -   60: auxiliary anode cell    -   W: aluminum plate    -   410: anodization treatment device    -   412: power supply tank    -   414: electrolytic treatment tank    -   416: aluminum plate    -   418, 426: electrolytic solution    -   420: power supply electrode    -   422, 428: roller    -   424: nip roller    -   430: electrolytic electrode    -   432: cell wall    -   434: DC power source    -   111: rotary brush roll    -   113: transport roll    -   114: transport guide plate    -   115: spray pipe    -   116: pipe line    -   117: filter    -   118: plate feed stand    -   119: plate discharge stand    -   120: developer tank    -   121: circulation pump    -   122: dryer    -   130: planographic printing plate precursor    -   1: aluminum plate    -   2, 4: roller-like brushes    -   3: polishing slurry liquid    -   5, 6, 7, 8: support roller

What is claimed is:
 1. A planographic printing plate precursor foron-press development comprising in the following order: an aluminumsupport; an image recording layer; and a protective layer, wherein athickness of the protective layer is 0.2 μm or greater, and in a casewhere a Bekk smoothness of a surface of an outermost layer at a sidewhere the image recording layer is provided is denoted by A seconds, thefollowing Expression (1) is satisfied; wherein an arithmetic averageheight Sa of a surface of an outermost layer at a side opposite to theside where the image recording layer is provided is in a range of 0.1 μmto 0.3 μm; and wherein the image recording layer contains an infraredabsorbing agent, a polymerization initiator, a polymerizable compound,and a polymer compound having a particle shape, and the polymer compoundhaving a particle shape is a thermoplastic polymer particle or amicrogel,A≤1000  (1).
 2. The planographic printing plate precursor for on-pressdevelopment according to claim 1, wherein the A seconds as the Bekksmoothness of the surface of the outermost layer at the side where theimage recording layer is provided satisfy the following Expression (2):A≤300  (2).
 3. The planographic printing plate precursor for on-pressdevelopment according to claim 1, wherein an arithmetic average heightSa of the surface of the outermost layer at the side where the imagerecording layer is provided is in a range of 0.3 μm to 20 μm.
 4. Theplanographic printing plate precursor for on-press development accordingto claim 1, wherein the protective layer contains particles having anaverage particle diameter of 0.5 μm to 20 μm, and an in-plane density ofthe particles is 10000 particles/mm² or less.
 5. The planographicprinting plate precursor for on-press development according to claim 4,wherein the average particle diameter of the particles is 1.3 times orgreater than the thickness of the protective layer.
 6. The planographicprinting plate precursor for on-press development according to claim 1,wherein the image recording layer contains particles having an averageparticle diameter of 0.5 μm to 20 μm, and an in-plane density of theparticles is 10000 particles/mm² or less.
 7. The planographic printingplate precursor for on-press development according to claim 4, whereinthe particles having the average particle diameter of 0.5 μm to 20 μmare at least one kind of particles selected from the group consisting oforganic resin particles and inorganic particles.
 8. The planographicprinting plate precursor for on-press development according to claim 6,wherein the particles having the average particle diameter of 0.5 μm to20 μm are at least one kind of particles selected from the groupconsisting of organic resin particles and inorganic particles.
 9. Theplanographic printing plate precursor for on-press development accordingto claim 1, wherein a plurality of protrusions containing a polymercompound as a main component are provided on the protective layer. 10.The planographic printing plate precursor for on-press developmentaccording to claim 1, wherein the polymer compound is a polymer compoundcontaining at least one of styrene and acrylonitrile as a constitutionalunit.
 11. The planographic printing plate precursor for on-pressdevelopment according to claim 1, wherein the image recording layercontains two or more kinds of polymerizable compounds.
 12. Theplanographic printing plate precursor for on-press development accordingto claim 1, wherein the protective layer contains a water-solublepolymer.
 13. The planographic printing plate precursor for on-pressdevelopment according to claim 12, wherein the water-soluble polymer ispolyvinyl alcohol having a saponification degree of 50% or greater. 14.The planographic printing plate precursor for on-press developmentaccording to claim 1, wherein a total value of the arithmetic averageheight Sa of the surface of the outermost layer at the side where theimage recording layer is provided and an arithmetic average height Sa ofa surface of an outermost layer at a side opposite to the side where theimage recording layer is provided is greater than 0.3 μm and 20 μm orless.
 15. The planographic printing plate precursor for on-pressdevelopment according to claim 1, wherein in a case where the Bekksmoothness of the surface of the outermost layer at the side where theimage recording layer is provided is denoted by A seconds and a Bekksmoothness of a surface of an outermost layer at a side opposite to theside where the image recording layer is provided is denoted by Bseconds, the following Expressions (1), (3), and (4) are satisfied:A≤1000  (1)B≤1000  (3)1/A+1/B≥0.002  (4).
 16. The planographic printing plate precursor foron-press development according to claim 1, comprising a back coat layerprovided at an opposite side of the aluminum support to the side wherethe image recording layer is provided.
 17. A key plate precursorcomprising: an aluminum support; and a protective layer, wherein athickness of the protective layer is 0.2 μm or greater, and in a casewhere a Bekk smoothness of a surface of an outermost layer at a sidewhere the protective layer is provided is denoted by A seconds, thefollowing Expression (1) is satisfied; wherein the key plate precursorfurther comprises a non-photosensitive layer between the aluminumsupport and the protective layer; and wherein an arithmetic averageheight Sa of a surface of an outermost layer at a side opposite to theside where the protective layer is provided is in a range of 0.1 μm to0.3 μm,A≤1000  (1),
 18. The key plate precursor according to claim 17, whereinan arithmetic average height Sa of the surface of the outermost layer atthe side where the protective layer is provided is in a range of 0.3 μmto 20 μm.
 19. The key plate precursor according to claim 17, comprisinga back coat layer provided at an opposite side of the aluminum supportto the side where the protective layer is provided.